Two friends are on the coordinate axis Ox in points with integer coordinates. One of them is in the point x1 = a, another one is in the point x2 = b. 

Each of the friends can move by one along the line in any direction unlimited number of times. When a friend moves, the tiredness of a friend changes according to the following rules: the first move increases the tiredness by 1, the second move increases the tiredness by 2, the third — by 3 and so on. For example, if a friend moves first to the left, then to the right (returning to the same point), and then again to the left his tiredness becomes equal to 1 + 2 + 3 = 6.

The friends want to meet in a integer point. Determine the minimum total tiredness they should gain, if they meet in the same point.

Input

The first line contains a single integer a (1 ≤ a ≤ 1000) — the initial position of the first friend. 

The second line contains a single integer b (1 ≤ b ≤ 1000) — the initial position of the second friend.

It is guaranteed that a ≠ b.

Output

Print the minimum possible total tiredness if the friends meet in the same point.

Examples

Input

3
4


Output

1


Input

101
99


Output

2


Input

5
10


Output

9

Note

In the first example the first friend should move by one to the right (then the meeting happens at point 4), or the second friend should move by one to the left (then the meeting happens at point 3). In both cases, the total tiredness becomes 1.

In the second example the first friend should move by one to the left, and the second friend should move by one to the right. Then they meet in the point 100, and the total tiredness becomes 1 + 1 = 2.

In the third example one of the optimal ways is the following. The first friend should move three times to the right, and the second friend — two times to the left. Thus the friends meet in the point 8, and the total tiredness becomes 1 + 2 + 3 + 1 + 2 = 9.
		     
		import java.io.*;
		        		    import java.math.*;
		        		    import java.util.*;
	import java.util.regex.Pattern;
	
	import javafx.scene.shape.Line;
		    	     
		        		    public class Main{
		        		  	private static InputStream stream;
		        		    	private static byte[] buf = new byte[1024];
		        		    	private static int curChar;
		        		    	private static int numChars;
		        		    	private static SpaceCharFilter filter;
		        		    	private static PrintWriter pw;
		        		    	private static long count = 0,mod=(long)1e9+7;
		        		    //	private static TreeSet<Integer> ts=new TreeSet[200000];
		public final static int INF = (int) 1E9;
		
		public static void main(String args[]) {
	    	
			InputReader(System.in);
			pw = new PrintWriter(System.out); 
		    new Thread(null ,new Runnable(){
		       public void run(){
		           try{
		        		
		               test();
	
		               pw.close();
		           } catch(Exception e){
		               e.printStackTrace();
		           }
		       }
		   },"1",1<<26).start();
		   	   }
		    static StringBuilder sb;
		    public static void test() throws IOException{
		    	 sb=new StringBuilder();
		    	
		    	 int t=1;
		    	 
		    	 while(t-->0){
		    		
		    		solve();
		    		//pw.println();
		    		//sb.append("\n");
		    	}
		    	//pw.println(sb);
		    }
		    
		    public static long pow(long n, long p,long mod) {
				if(p==0)
					return 1;
				if(p==1)
					return n%mod;
				if(p%2==0){
					long temp=pow(n, p/2,mod);
				return (temp*temp)%mod;
				}else{
					 	long temp=pow(n,p/2,mod);
					 	temp=(temp*temp)%mod;
					 	return(temp*n)%mod;
					 	
				}
			}
		    public static long pow(long n, long p) {
				if(p==0)
					return 1;
				if(p==1)
					return n;
				if(p%2==0){
					long temp=pow(n, p/2);
				return (temp*temp);
				}else{
					 	long temp=pow(n,p/2);
					 	temp=(temp*temp);
					 	return(temp*n);
					 	
				}
			}
		    public static void Merge(long a[],int p,int r){
		        if(p<r){
		            int q = (p+r)/2;
		            Merge(a,p,q);
		            Merge(a,q+1,r);
		            Merge_Array(a,p,q,r);
		        }
		    }
		    public static void Merge_Array(long a[],int p,int q,int r){
		       long b[] = new long[q-p+1];
		        long c[] = new long[r-q];
		        for(int i=0;i<b.length;i++)
		            b[i] = a[p+i];
		        for(int i=0;i<c.length;i++)
		            c[i] = a[q+i+1];
		        int i = 0,j = 0;
		        for(int k=p;k<=r;k++){
		            if(i==b.length){
		                a[k] = c[j];
		                j++;
		            }
		            else if(j==c.length){
		                a[k] = b[i];
		                i++;
		            }
		            else if(b[i]<c[j]){
		                a[k] = b[i];
		                i++;
		            }
		            else{
		                a[k] = c[j];
		                j++;
		            }
		        }
		    }
		    
		  
			public static long gcd(long x, long y) {
				if (x == 0)
					return y;
				else
					return gcd( y % x,x);
			}	
			
			public static boolean isPrime(int n) {
				if (n <= 1)
					return false;
				if (n <= 3)
					return true;
		 
				if (n % 2 == 0 || n % 3 == 0)
					return false;
		 
				for (int i = 5; i * i <= n; i = i + 6)
					if (n % i == 0 || n % (i + 2) == 0)
						return false;
		 
				return true;
			}
			
		        static LinkedList<Integer> adj[],adj2[];
		        static boolean Visited[];
		        static HashSet<Integer> exc;
		        static long oddsum[]=new long[1000001];
		        static long co=0;
		        static int indeg[],outdeg[];
  		      
		    
		    	private static void buildgraph(int n){
		    		adj=new LinkedList[n+1];
		    		adj2=new LinkedList[n+1];
		    		Visited=new boolean[n+1];
		    		levl=new int[n+1];
		    		indeg=new int[n+1];
		    		outdeg=new int[n+1];
		    		for(int i=0;i<=n;i++){
		    			adj[i]=new LinkedList<Integer>();
		    			adj2[i]=new LinkedList<Integer>();
		    		}
		
		
		    	}
		      
		       
		        static int[] levl;
		        static int[] eat;
		        static int n,m;
		        static int price[];
		        //ind frog crab
		    
		        
		        static long d,x,y;
				static long modInverse(long A, long M)
				{
				extendedEuclid(A,M);
				return (x%M+M)%M;    //x may be negative
				}
				static void extendedEuclid(long A, long B) {
				if(B == 0) {
				d = A;
				x = 1;
				y = 0;
				}
				else {
				extendedEuclid(B, A%B);
				long temp = x;
				x = y;
				y = temp - (A/B)*y;
				}
				}
		        static double distance(int x1,int y1,int x2,int y2){
		        	return Math.sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
		        }
		        static double area(int x1, int y1, int x2, int y2, int x3, int y3)
		        {
		           return Math.abs((x1*(y2-y3) + x2*(y3-y1)+ x3*(y1-y2))/2.0);
		        }
		        static boolean isInside(int x1, int y1, int x2, int y2, int x3, int y3, int x, int y)
		        {   
		           double A = area (x1, y1, x2, y2, x3, y3);
		         
		           double A1 = area (x, y, x2, y2, x3, y3);
		         
		           double A2 = area (x1, y1, x, y, x3, y3);
		         
		           double A3 = area (x1, y1, x2, y2, x, y);
		           
		          return (A == A1 + A2 + A3);
		        }
		      
				static int col[];
		    public static boolean isVowel(char c){
		    	if(c=='a' || c=='e'||c=='i' || c=='o' || c=='u')
		    		return true;
		    	return false;
		    }
		static long arr[], lazy[],ans[];
		static int c[],nodes[];
		static int dp[][];
		static long a[][];
		
		private static boolean isPrim(long n,int p){
			for (long i = 2; i * i <= n; i++) {
		        if (n % i == 0 && i <= p) return false;
		    }
		    return true;
		}
		//price - starting index of string with given hash
		//rating-count of number of time of a hash
		static ArrayList<String> all_perm;
		static boolean[][] visited1;
		static  boolean won;
		static boolean containsCycle;
		static ArrayList<Integer> anss;
		private static int size = 0;
		public static void solve() throws IOException{
			HashSet<Integer> prime = new HashSet<Integer>();
			for(int i=2;i<=1;i++){
				if(isPrime(i)){
					prime.add(i);
				}
			}
			
			int a=nextInt();
			int b=nextInt();
			if(Math.abs(a-b)==1){
				pw.println(1);
				return;
			}
			int tempa=Math.min(a, b);
			int tempb=Math.max(a, b);
			long ans=Long.MAX_VALUE;
			for(int i=tempa;i<=tempb;i++){
				int dist_from_a = i-tempa;
				int dist_from_b = tempb-i;
				long tota  = dist_from_a*(dist_from_a+1);
				tota/=2;
				long totb = dist_from_b*(dist_from_b+1);
				totb/=2;
				ans=Math.min(ans,totb+tota);
			}
			pw.print(ans);
		}
		
				private static boolean check(int x,int y,int n,int m){
			if(x>=0 && x<n && y>=0 && y<m)
				return true;
			return false;
		}
				
				
				
				private static void dfs(int curr,int par){
			Visited[curr]=true;
			for(int i:adj[curr]){
				if(!Visited[i]){
					dfs(i,curr);
				}
			}
			dp[curr][nodes[curr]]++;
			for(int i=0;i<26;i++){
				dp[par][i]+=dp[curr][i];
			}
		}
	
		
		
		    private static boolean Check(int x,int y,int n){
				if(x>=0 && x<n && y>=0 && y<n)
					return true;
				return false;
			}
		    
		    public static String reverseString(String s) {
				StringBuilder sb = new StringBuilder(s);
				sb.reverse();
				return (sb.toString());
			}
		    
		  /*  
		   private static void BFS(int sou){
		    	Queue<Integer> q=new LinkedList<Integer>();
		    	q.add(sou);
		    	Visited[sou]=true;
		    	levl[sou]=0;
		    	while(!q.isEmpty()){
		    		int top=q.poll();
		    		
		    		for(int i:adj[top]){
		    			//pw.println(i+" "+top);
					if(!Visited[i])
					{
						
						q.add(i);
						levl[i]=levl[top]+1;
					}
					
					Visited[i]=true;
					
					}
				}
			}*/
			
		
		
		
		    		      
		    		   /* private static void kahn(int n){
		    		    	
		    		    	PriorityQueue<Integer> q=new PriorityQueue<Integer>();
		    				for(int i=1;i<=n;i++){
		    					if(indeg[i]==0){
		    						q.add(i);
		    					}
		    				}
		    				while(!q.isEmpty()){
		    					int top=q.poll();
		    					st.push(top);
		    					for(Node i:adj[top]){
		    						indeg[i.to]--;
		    						if(indeg[i.to]==0){
		    							q.add(i.to);
		    						}
		    					}
		    				}
		    		    }
		    		        
		    		        static int state=1;
		    		        static long no_exc=0,no_vert=0;
		    		      static Stack<Integer> st;
		    		      static HashSet<Integer> inset;
		    		     /*   private static void topo(int curr){
		    		        	
		    		        	Visited[curr]=true;
		    		        	inset.add(curr);
		    		        	for(int x:adj[curr]){
		    		        		if(adj[x].contains(curr) || inset.contains(x)){
		    		        			state=0;
		    		        			return;
		    		        		}
		    		        		if(state==0)
		    		        			return;
		    		        		
		    		        	}
		    		        	st.push(curr);
		    		        	
		    		        	inset.remove(curr);
		    		        }*/
		    		        static HashSet<Integer> hs;
		    		       
		    		     
		    		     	static boolean prime[];
							static int spf[];
							public static void sieve(int n){
								prime=new boolean[n+1];
								spf=new int[n+1];
								
								Arrays.fill(spf, 1);
								Arrays.fill(prime, true);
							prime[1]=false;
								spf[2]=2;
								
							for(int i=4;i<=n;i+=2){
								spf[i]=2;
							}
							for(int i=3;i<=n;i+=2){
								if(prime[i]){
									spf[i]=i;
									for(int j=2*i;j<=n;j+=i){
										
										prime[j]=false;
									if(spf[j]==1){
										spf[j]=i;
									}
									}
								}
							}
							
								
							}
		    		     	
		    		    	// To Get Input
		// Some Buffer Methods
		 
		    		     	public static void sort(long a[]){
		    		     		Merge(a, 0, a.length-1);
		    		     	}
		    		    	public static void InputReader(InputStream stream1) {
		    		    		stream = stream1;
		    		    	}
		 
		    		    	private static boolean isWhitespace(int c) {
		    		    		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		    		    	}
		 
		    		    	private static boolean isEndOfLine(int c) {
		    		    		return c == '\n' || c == '\r' || c == -1;
		    		    	}
		 
		    		    	private static int read() {
		    		    		if (numChars == -1)
		    		    			throw new InputMismatchException();
		    		    		if (curChar >= numChars) {
		    		    			curChar = 0;
		    		    			try {
		    		    				numChars = stream.read(buf);
		    		    			} catch (IOException e) {
		    		    				throw new InputMismatchException();
		    		    			}
		    		    			if (numChars <= 0)
		    		    				return -1;
		    		    		}
		    		    		return buf[curChar++];
		    		    	}
		 
		    		    	private static int nextInt() {
		    		    		int c = read();
		    		    		while (isSpaceChar(c))
		    		    			c = read();
		    		    		int sgn = 1;
		    		    		if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
		    		    			c = read();
		    		    		} while (!isSpaceChar(c));
		    		    		return res * sgn;
		    		    	}
		 
		    		    	private static long nextLong() {
		    		    		int c = read();
		    		    		while (isSpaceChar(c))
		    		    			c = read();
		    		    		int sgn = 1;
		    		    		if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
		    		    			c = read();
		    		    		} while (!isSpaceChar(c));
		    		    		return res * sgn;
		    		    	}
		 
		    		    	private static String nextToken() {
		    		    		int c = read();
		    		    		while (isSpaceChar(c))
		    		    			c = read();
		    		    		StringBuilder res = new StringBuilder();
		    		    		do {
		    		    			res.appendCodePoint(c);
		    		    			c = read();
		    		    		} while (!isSpaceChar(c));
		    		    		return res.toString();
		    		    	}
		 
		    		    	private static String nextLine() {
		    		    		int c = read();
		    		    		while (isSpaceChar(c))
		    		    			c = read();
		    		    		StringBuilder res = new StringBuilder();
		    		    		do {
		    		    			res.appendCodePoint(c);
		    		    			c = read();
		    		    		} while (!isEndOfLine(c));
		    		    		return res.toString();
		    		    	}
		 
		    		    	private static int[] nextIntArray(int n) {
		    		    		int[] arr = new int[n];
		    		    		for (int i = 0; i < n; i++) {
		    		    			arr[i] = nextInt();
		    		    		}
		    		    		return arr;
		    		    	}
		 
		    		    	private static long[][] next2dArray(int n, int m) {
		    		    		long[][] arr = new long[n][m];
		    		    		for (int i = 0; i < n; i++) {
		    		    			for (int j = 0; j < m; j++) {
		    		    				arr[i][j] = nextLong();
		    		    			}
		    		    		}
		    		    		return arr;
		    		    	}
		    		    	private static char[][] nextCharArray(int n,int m){
		    		    		char [][]c=new char[n][m];
		    		    		for(int i=0;i<n;i++){
		    		    			String s=nextLine();
		    		    			for(int j=0;j<s.length();j++){
		    		    				c[i][j]=s.charAt(j);
		    		    			}
		    		    		}
		    		    		return c;
		    		    	}
		 
		    		    	private static long[] nextLongArray(int n) {
		    		    		long[] arr = new long[n];
		    		    		for (int i = 0; i < n; i++) {
		    		    			arr[i] = nextLong();
		    		    		}
		    		    		return arr;
		    		    	}
		 
		    		    	private static void pArray(int[] arr) {
		    		    		for (int i = 0; i < arr.length; i++) {
		    		    			pw.print(arr[i] + " ");
		    		    		}
		    		    		pw.println();
		    		    		return;
		    		    	}
		 
		    		    	private static void pArray(long[] arr) {
		    		    		for (int i = 0; i < arr.length; i++) {
		    		    			pw.print(arr[i] + " ");
		    		    		}
		    		    		pw.println();
		    		    		return;
		    		    	}
		 
		    		    	private static void pArray(boolean[] arr) {
		    		    		for (int i = 0; i < arr.length; i++) {
		    		    			pw.print(arr[i] + " ");
		    		    		}
		    		    		pw.println();
		    		    		return;
		    		    	}
		 
		    		    	private static boolean isSpaceChar(int c) {
		    		    		if (filter != null)
		    		    			return filter.isSpaceChar(c);
		    		    		return isWhitespace(c);
		    		    	}
		 
		    		    	private interface SpaceCharFilter {
		    		    		public boolean isSpaceChar(int ch);
		    		    	}
		    		    	
		
		}
		    		    
		    		        class Node{
		    		    	int to;
		    		    	long dist;
		    		    	Node(int to,long dist){
		    		    		this.to=to;
		    		    		this.dist=dist;
		    		    	}
		    		    	
		    		    }
		    		        class Qu{
		    		    		long a0,a1,a2,a3;
		    		    		public Qu(long a0,long a1,long a2,long a3) {
		    		    			this.a0=a0;
		    		    			this.a1=a1;
		    		    			this.a2=a2;
		    		    			this.a3=a3;
		    		    		}
		    		    }
		    		
		class Dsu{
		private int rank[], parent[] ,n;
		long str[],si[],larg[];
		long max=0;
		int cnt=0;
		private static int[] parent1;
		Dsu(int size){
			this.n=size+1;
			rank=new int[n];
			cnt=n-1;
			//parent=new int[n];
		    		    		    		parent=new int[n];
		    		    		    		str=new long[n];
		    		    		    		si=new long[n];
		    		    		
		    		    		    		larg=new long[n];
		    		    		    		makeSet();
		    		    		
		    		    		    	}
		    		    		    	
		    		    		    	void makeSet(){
		    		    		    		for(int i=0;i<n;i++){
		    		    		    			parent[i]=i;
		    		    		    			si[i]=1;
		    		    		    		}
		    		    		    	}
		    		    		    	
		    		    		    	int find(int x){
		    		    		    		if(parent[x]!=x){
		    		    		    			
		    		    		    			parent[x]=find(parent[x]);
		    		    		    		}
		    		    		    		return parent[x];
		    		    		    	}
		    		    		    	
		    		    		    	void join(int ind,long val){
		    		    		    		if(str[ind]==0){
		    		    		    			str[ind]=val;
		    		    		    			larg[ind]=val;
		    		    		    			max=Math.max(max, str[ind]);
		    		    		    		}
		    		    		    		int prev_ind=(ind-1);
		    		    		    		int next_ind=(ind+1);
		    		    		    		if(prev_ind>0 && larg[prev_ind]!=0){
		    		    		    			union(prev_ind,ind);
		    		    		    		}
		    		    		    		if(next_ind<n && larg[next_ind]!=0){
		    		    		    			union(next_ind,ind);
		    		    		    		}
		    		    		    		
		    		    		    	}
		    		    		    
		    		    		    	
		    		    		    	boolean union(int x,int y){
		    		    		    		int xRoot=find(x);
		    		    		    		int yRoot=find(y);
		    		    		    
		    		    		    	
		    		    		    		if(xRoot==yRoot)
		    		    		    			return false;
		    		    		    		if(rank[xRoot]<rank[yRoot]){
		    		    		    		parent[xRoot]=yRoot;
		    		    		    		
		    		    		    		larg[yRoot]=Math.max(larg[xRoot], larg[yRoot]);
		    		    		    		
		    		    		    		si[yRoot]+=si[xRoot];
		    		    		    		str[yRoot]=larg[yRoot]*si[yRoot];
		    		    		    			max=Math.max(str[yRoot], max);
		    		    		    		}else if(rank[yRoot]<rank[xRoot]){
		    		    		    			parent[yRoot]=xRoot;
		     
		    		    		    			larg[xRoot]=Math.max(larg[xRoot], larg[yRoot]);
		        		    		    		
		        		    		    		si[xRoot]+=si[yRoot];
		        		    		    		str[xRoot]=larg[xRoot]*si[xRoot];
		    			    		    		max=Math.max(str[xRoot], max);
		    		    		    		}else{
		    		    		    			parent[yRoot]=xRoot;
		    		    		    			rank[xRoot]++;
		     
		    		    		    			larg[xRoot]=Math.max(larg[xRoot], larg[yRoot]);
		        		    		    		
		        		    		    		si[xRoot]+=si[yRoot];
		        		    		    		str[xRoot]=larg[xRoot]*si[xRoot];
		    			    		    		max=Math.max(str[xRoot], max);
		    		    		    		
		    		    		    		}
		    		    		    		cnt--;
		    		    		    		return true;
		    		    		    	}
		    	
		    		    		     
		    		    		    }
	class Pair1 implements Comparable<Pair1>{
			long price,rating;
			Pair1(long a,long b){
				this.price=a;
				this.rating=b;
			}
			@Override
			public int compareTo(Pair1 arg0) {
				
					return (int)(price-arg0.price);
				
			}
		
		
		}
		  
		
