You are playing another computer game, and now you have to slay n monsters. These monsters are standing in a circle, numbered clockwise from 1 to n. Initially, the i-th monster has a_i health.

You may shoot the monsters to kill them. Each shot requires exactly one bullet and decreases the health of the targeted monster by 1 (deals 1 damage to it). Furthermore, when the health of some monster i becomes 0 or less than 0, it dies and explodes, dealing b_i damage to the next monster (monster i + 1, if i < n, or monster 1, if i = n). If the next monster is already dead, then nothing happens. If the explosion kills the next monster, it explodes too, damaging the monster after it and possibly triggering another explosion, and so on.

You have to calculate the minimum number of bullets you have to fire to kill all n monsters in the circle.

Input

The first line contains one integer T (1 ≤ T ≤ 150000) — the number of test cases.

Then the test cases follow, each test case begins with a line containing one integer n (2 ≤ n ≤ 300000) — the number of monsters. Then n lines follow, each containing two integers a_i and b_i (1 ≤ a_i, b_i ≤ 10^{12}) — the parameters of the i-th monster in the circle.

It is guaranteed that the total number of monsters in all test cases does not exceed 300000.

Output

For each test case, print one integer — the minimum number of bullets you have to fire to kill all of the monsters.

Example

Input


1
3
7 15
2 14
5 3


Output


6
/*
ID: abdelra29
LANG: JAVA
TASK: skidesign
*/
import java.util.*;
import java.math.*;
import java.io.*; 
 public class B{
static int[] dx = new int[]{-1,0,1,0};
    static int[] dy = new int[]{0,1,0,-1};
    static FastReader scan=new FastReader();
   public static PrintWriter out = new PrintWriter (new BufferedOutputStream(System.out));
  static ArrayList<Pair>es;
  static LinkedList<Integer>edges[];
  static Set<Pair>edges2[][];

   static boolean prime[];
   static void sieve(int n) 
    { 
        
        prime = new boolean[n+1]; 
        for(int i=0;i<n;i++) 
            prime[i] = true; 
          
        for(int p = 2; p*p <=n; p++) 
        { 
           
            if(prime[p] == true) 
            { 
                
                for(int i = p*p; i <= n; i += p) 
                    prime[i] = false; 
            } 
        } 
          
        
    }      
     public static int lowerBound(int[] array, int length, int value) {
        int low = 0;
        int high = length;
        while (low < high) {
            final int mid = (low + high) / 2;
            //checks if the value is less than middle element of the array
            if (value <= array[mid]) {
                high = mid;
            } else {
                low = mid+1 ;
            }
        }
        return low;
    }
    public static int upperBound(int[] array, int length, int value) {
        int low = 0;
        int high = length;
        while (low < high) {
            final int mid = low+(high-low) / 2;
            if ( array[mid]>value) {
                high = mid ;
            } else {
                low = mid+1;
            }
        }
        return low;
    }
static long mod(long x,long y)
    {
        if(x<0)
            x=x+(-x/y+1)*y;
        return x%y;
    }    
     static boolean isPowerOfTwo(long n) 
    { 
        if (n == 0) 
            return false; 
  
        while (n != 1) { 
            if (n % 2 != 0) 
                return false; 
            n = n / 2; 
        } 
        return true; 
    } 

  
   
static boolean isprime(long x)
           {
            for(long i=2;i*i<=x;i++)
                if(x%i==0)
                    return false;
                return true;
           }


static int dist(int x1,int y1,int x2,int y2){
return Math.abs(x1-x2)+Math.abs(y1-y2);
}


    static long cuberoot(long x)
    {
        long lo = 0, hi = 1000005;
        while(lo<hi)
        {
            long m = (lo+hi+1)/2;
            if(m*m*m>x)
                hi = m-1;
            else
                lo = m;
        }
        return lo;
    }
     public static int log2(int N) 
    { 
  
        // calculate log2 N indirectly 
        // using log() method 
        int result = (int)(Math.log(N) / Math.log(2)); 
  
        return result; 
    } 
  
    
   
       static long gcd(long a, long b) {
    if(a!=0&&b!=0)
        while((a%=b)!=0&&(b%=a)!=0);
    return a^b;
}
    static long LCM(long a,long b){
    return (Math.abs(a*b))/gcd(a,b);
   }
   static int mid;
   public static class comp1 implements Comparator<ArrayList<Integer>>{  
public int compare(ArrayList<Integer> o1,ArrayList<Integer> o2){
    return (int)(o2.size()-o1.size());
}
  }

     public static class comp2 implements Comparator<Pair>{  
public int compare(Pair o1,Pair o2){
 
return (int)((o1.x+o1.y*mid)-(o2.x+o2.y*mid));
}
  }

   static boolean collinear(long x1, long y1, long x2,  
                          long y2, long x3, long y3) 
{
    long a = x1 * (y2 - y3) +  
                x2 * (y3 - y1) +  
                x3 * (y1 - y2); 
                if(a==0)
                    return true;
                return false;
}

static int ceil(int a,int b)
{
    if(a%b!=0)
        return (a/b)+1;
    else return a/b;
}

public static void main(String[] args)  throws Exception 
{
    /*int xx=253;
    for(int i=1;i*i<=xx;i++)
    {
        if(xx%i==0)
        {
            System.out.println(i);
            System.out.println(xx/i);
        }
    }*/
//java.util.Scanner scan=new java.util.Scanner(new File("mootube.in"));
// PrintWriter out = new PrintWriter (new FileWriter("mootube.out"));
//scan=new FastReader("skidesign.in");
//out = new PrintWriter ("skidesign.out");
//System.out.println(3^2);
//System.out.println(19%4);
   //StringBuilder news=new StringBuilder("ab");
   //news.deleteCharAt(1);
   //news.insert(0,'c');
   //news.deleteCharAt(0);
   //System.out.println(news);
   //System.out.println(can(2,15));
    //System.out.println(LCM(2,2));
  // System.out.println(31^15);
 //System.out.println("");
   //System.out.println(824924296372176000L>(long)1e16);
int tt=1;
//rec(2020);
//System.out.println(Long.MAX_VALUE);
//System.out.println(Integer.MAX_VALUE);
//int st=scan.nextInt();
//System.out.println(calc(91));
//sieve(21000);

//SNWNSENSNNSWNNW

   // System.out.println(set.remove(new Pair(1,1)));
//System.out.println(count("cccccccccccccccccccccccccooooooooooooooooooooooooodddddddddddddeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffforrrrrrrrrrrrrcesssssssssssss","codeforces"));
  //S0ystem.out.println(isPowerOfTwo(446265625L));
//System.out.println("daaa".compareTo("bccc"));
//System.out.println(2999000999L>1999982505L);
//System.out.println("?bac?bac??a?a?a?abac????abacab?ca?a".length());
//StringBuilder s=new StringBuilder("");
//tt=scan.nextInt();
//String ok="ABDC";
//System.out.println(ok.substring(2));
//System.out.println(2000000000/2);
tt=scan.nextInt();
//System.out.println(LCM(4,6));
//System.out.println(isprime(23335));
//int T=1;


  outer:while(tt-->0)
 {
int n=scan.nextInt();
ArrayList<Long>arr[]=new ArrayList[n];
for(int i=0;i<n;i++)
arr[i]=new ArrayList();
ArrayList<Pair>pairs=new ArrayList<Pair>();
int k=0;
int l=0;
for(int i=0;i<n;i++)
{
    pairs.add(new Pair(scan.nextLong(),scan.nextLong()));
}
long sum=0;
long tmp[]=new long [n];
for(int i=1;i<n;i++)
{
    tmp[i]=(Math.max(0L,pairs.get(i).x-pairs.get(i-1).y));
    sum+=(Math.max(0L,pairs.get(i).x-pairs.get(i-1).y));
}
tmp[0]=Math.max(0L,pairs.get(0).x-pairs.get(n-1).y);
//out.println(pairs.get(0).x+" "+pairs.get(n-1).y);
sum+=Math.max(0L,pairs.get(0).x-pairs.get(n-1).y);
long ans=Long.MAX_VALUE;
//out.println(sum);
for(int i=0;i<n;i++)
{
    ans=Math.min(ans,sum+pairs.get(i).x-tmp[i]);
}
out.println(ans);
}
out.close();



}

static class dsu{
    static int id[]=new int[101];
    dsu()
    {
        for(int i=0;i<101;i++)
            id[i]=i;
    }
    static int find(int x)
    {
        if(x==id[x])
            return x;
        return find(id[x]);
    }
    static void connect(int i,int j)
    {
        i=find(i);
        j=find(j);
        id[i]=j;
    }
    static boolean is(int i,int j)
    {
        return find(i)==find(j);
    }
}
static long binexp(long a,long n,long mod)
{
    if(n==0)
       return 1;
    long res=binexp(a,n/2,mod)%mod;
    res=res*res;
    if(n%2==1)
        return (res*a)%mod;
    else 
        return res%mod;
}
static class special{
    Pair x;
    Pair y;
    special(Pair x,Pair y)
    {
      this.x=new Pair(x.x,x.y);
      this.y=new Pair(y.x,y.y);
    }   
      @Override
        public int hashCode() {
            return (int)(x.x + 31 * y.y);
        }
        public boolean equals(Object other)
    {
        if(other instanceof special)
        {
            special e =(special)other;
            return this.x.x==e.x.x && this.x.y==e.x.y && this.y.x==e.y.x && this.y.y==e.y.y;
        }
        else return false;
    }
}
static long powMod(long base, long exp, long mod) {
       if (base == 0 || base == 1) return base;
       if (exp == 0) return 1;
       if (exp == 1) return base % mod;
       long R = powMod(base, exp/2, mod) % mod;
       R *= R;
       R %= mod;
       if ((exp & 1) == 1) {
           return base * R % mod;
       }
       else return R % mod;
   }
 public static  long pow(long b, long e) {
            long r = 1;
            while (e > 0) {
                if (e % 2 == 1) r = r * b ;
                b = b * b;
                e >>= 1;
            }
            return r;
        }

private static void sort(int[] arr) {
        List<Integer> list = new ArrayList<>();
        for (int object : arr) list.add(object);
        Collections.sort(list);
        for (int i = 0; i < list.size(); ++i) arr[i] = list.get(i);
    }
 public static class FastReader {
        BufferedReader br;
        StringTokenizer root;
        
 
        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        FastReader(String filename)throws Exception
        {

            br=new BufferedReader(new FileReader(filename));
        }
 
        String next() {
            while (root == null || !root.hasMoreTokens()) {
                try {
                    root = new StringTokenizer(br.readLine());
                } catch (Exception addd) {
                    addd.printStackTrace();
                }
            }
            return root.nextToken();
        }
 
        int nextInt() {
            return Integer.parseInt(next());
        }
 
        double nextDouble() {
            return Double.parseDouble(next());
        }
 
        long nextLong() {
            return Long.parseLong(next());
        }
 
        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (Exception addd) {
                addd.printStackTrace();
            }
            return str;
        }
         public int[] nextIntArray(int arraySize) {
            int array[] = new int[arraySize];
 
            for (int i = 0; i < arraySize; i++) {
                array[i] = nextInt();
            }
 
            return array;
        }
}
public static class Pair implements Comparable<Pair>{
         long x;
         long y;
         long ab;
        
        long z;
        public Pair(){}
        public Pair(long x1, long y1,long z) {
            x=x1;
            y=y1;
            this.z=z;
        }
        public Pair(long x1, long y1) {
            x=x1;
            y=y1;
            this.ab=x+y;
        
        }
        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result +(int) x;
            result = prime * result + (int)y;
            return result;
        }
        public String toString() {
            return x + " " + y;
        }
        @Override
        public boolean equals(Object o){
            if (o == this) return true;
            if(o==null)
                return false;
            if (o.getClass() != getClass()) return false;
            Pair t = (Pair)o;
            return t.x == x && t.y == y&&t.z==z;
        }
        public  int compareTo(Pair o)
        {
            return (int)(z-o.z);
        }
}

}







