You have a multiset containing several integers. Initially, it contains a_1 elements equal to 1, a_2 elements equal to 2, ..., a_n elements equal to n.

You may apply two types of operations:

  * choose two integers l and r (l ≤ r), then remove one occurrence of l, one occurrence of l + 1, ..., one occurrence of r from the multiset. This operation can be applied only if each number from l to r occurs at least once in the multiset; 
  * choose two integers i and x (x ≥ 1), then remove x occurrences of i from the multiset. This operation can be applied only if the multiset contains at least x occurrences of i. 



What is the minimum number of operations required to delete all elements from the multiset?

Input

The first line contains one integer n (1 ≤ n ≤ 5000).

The second line contains n integers a_1, a_2, ..., a_n (0 ≤ a_i ≤ 10^9).

Output

Print one integer — the minimum number of operations required to delete all elements from the multiset.

Examples

Input


4
1 4 1 1


Output


2


Input


5
1 0 1 0 1


Output


3

import java.util.*;
import java.util.PrimitiveIterator.OfDouble;
import java.io.*;


public class E {
    
    static int mod = (int) (1e9+7);
    static InputReader in;
    static PrintWriter out;
    
    
    static int solve(int l, int r, int[] arr) {
    	if(l > r) return 0;
    	int ans = r - l + 1;
    	int min = Integer.MAX_VALUE;
    	int idx = l;
    	for(int i = l; i <= r; i++) {
    		if(min > arr[i]) {
    			idx = i;
    			min = arr[i];
    		}
    	}
    	
    	for(int i = l; i <= r; i++) {
    		arr[i] -= min;
    	}
    	
    	int jdx = l;
    	while(jdx <= r && arr[jdx] == 0) jdx++;
    	
    	int kdx = jdx;
    	while(kdx <=r  && arr[kdx] != 0) kdx++;
    	
    	min += solve(jdx, kdx - 1, arr) + solve(kdx + 1, r, arr);
    	if(min > ans) {
    		for(int i = l; i <= r; i++) arr[i] += arr[idx];
    	}
    	return min(ans, min);
    }
    
    static void solve()
    {
 
        in = new InputReader(System.in);
        out = new PrintWriter(System.out); 
        
    	int n = in.nextInt();
    	int[] arr = in.nextIntArray(n);
    	
    	out.println(solve(0, n - 1, arr));
        out.close();
        
    }
    
    public static void main(String[] args) {
        new Thread(null ,new Runnable(){
            public void run()
            {
                try{
                    solve();
                } catch(Exception e){
                    e.printStackTrace();
                }
            }
        },"1",1<<26).start();
    }
    
    static int[][] graph(int from[], int to[], int n)
    {
        int g[][] = new int[n][];
        int cnt[] = new int[n];
        for (int i = 0; i < from.length; i++) {
            cnt[from[i]]++;
            cnt[to[i]]++;
        }
        for (int i = 0; i < n; i++) {
            g[i] = new int[cnt[i]];
        }
        Arrays.fill(cnt, 0);
        for (int i = 0; i < from.length; i++) {
            g[from[i]][cnt[from[i]]++] = to[i];
            g[to[i]][cnt[to[i]]++] = from[i];
        }
        return g;
    }
    
    static class Pair implements Comparable<Pair>{

        int x,y,i;
        
		Pair (int x,int y,int i){
			this.x=x;
			this.y=y;
			this.i=i;
		}

		Pair (int x,int y){
			this.x=x;
			this.y=y;
		}
	        
		public int compareTo(Pair o) {
			return Integer.compare(this.x,o.x);
			//return 0;
		}

        public boolean equals(Object o) {
            if (o instanceof Pair) {
                Pair p = (Pair)o;
                return p.x == x && p.y == y && p.i==i;
            }
            return false;
        }
        public int hashCode() {
            return new Integer(x).hashCode() * 31 + new Integer(y).hashCode()+new Integer(i).hashCode()*37;
        }
        
        @Override
        public String toString() {
        	return x + " " + y;
        }
    
    } 
    
    static String rev(String s) {
        StringBuilder sb = new StringBuilder(s);
        sb.reverse();
        return sb.toString();
    }

    static long gcd(long x, long y) {
        if (y == 0) {
            return x;
        } else {
            return gcd(y, x % y);
        }
    }

    static int gcd(int x, int y) {
        if (y == 0) {
            return x;
        } else {
            return gcd(y, x % y);
        }
    }
    
    static int abs(int a, int b) {
        return (int) Math.abs(a - b);
    }

    static long abs(long a, long b) {
        return (long) Math.abs(a - b);
    }

    static int max(int a, int b) {
        if (a > b) {
            return a;
        } else {
            return b;
        }
    }

    static int min(int a, int b) {
        if (a > b) {
            return b;
        } else {
            return a;
        }
    }

    static long max(long a, long b) {
        if (a > b) {
            return a;
        } else {
            return b;
        }
    }

    static long min(long a, long b) {
        if (a > b) {
            return b;
        } else {
            return a;
        }
    }

    static long pow(long n, long p, long m) {
        long result = 1;
        if (p == 0) {
            return 1;
        }
        while (p != 0) {
            if (p % 2 == 1) {
                result *= n;
            }
            if (result >= m) {
                result %= m;
            }
            p >>= 1;
            n *= n;
            if (n >= m) {
                n %= m;
            }
        }
        return result;
    }

    static long pow(long n, long p) {
        long result = 1;
        if (p == 0) {
            return 1;
        }
        if (p == 1) {
            return n;
        }
        while (p != 0) {
            if (p % 2 == 1) {
                result *= n;
            }
            p >>= 1;
            n *= n;
        }
        return result;
    }
   
    static void debug(Object... o) {
            System.out.println(Arrays.deepToString(o));
    }

    static class InputReader
    {

        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream)
        {
                this.stream = stream;
        }

        public int snext()
        {
                if (snumChars == -1)
                        throw new InputMismatchException();
                if (curChar >= snumChars)
                {
                        curChar = 0;
                        try
                        {
                                snumChars = stream.read(buf);
                        } catch (IOException e)
                        {
                                throw new InputMismatchException();
                        }
                        if (snumChars <= 0)
                                return -1;
                }
                return buf[curChar++];
        }

        public int nextInt()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                int sgn = 1;
                if (c == '-')
                {
                        sgn = -1;
                        c = snext();
                }
                int res = 0;
                do
                {
                        if (c < '0' || c > '9')
                                throw new InputMismatchException();
                        res *= 10;
                        res += c - '0';
                        c = snext();
                } while (!isSpaceChar(c));
                return res * sgn;
        }

        public long nextLong()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                int sgn = 1;
                if (c == '-')
                {
                        sgn = -1;
                        c = snext();
                }
                long res = 0;
                do
                {
                        if (c < '0' || c > '9')
                                throw new InputMismatchException();
                        res *= 10;
                        res += c - '0';
                        c = snext();
                } while (!isSpaceChar(c));
                return res * sgn;
        }

        public int[] nextIntArray(int n)
        {
                int a[] = new int[n];
                for (int i = 0; i < n; i++)
                {
                        a[i] = nextInt();
                }
                return a;
        }

        public long[] nextLongArray(int n)
        {
                long a[] = new long[n];
                for (int i = 0; i < n; i++)
                {
                        a[i] = nextLong();
                }
                return a;
        }

        public String readString()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                StringBuilder res = new StringBuilder();
                do
                {
                        res.appendCodePoint(c);
                        c = snext();
                } while (!isSpaceChar(c));
                return res.toString();
        }

        public String nextLine()
        {
                int c = snext();
                while (isSpaceChar(c))
                        c = snext();
                StringBuilder res = new StringBuilder();
                do
                {
                        res.appendCodePoint(c);
                        c = snext();
                } while (!isEndOfLine(c));
                return res.toString();
        }

        public boolean isSpaceChar(int c)
        {
                if (filter != null)
                        return filter.isSpaceChar(c);
                return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private boolean isEndOfLine(int c)
        {
                return c == '\n' || c == '\r' || c == -1;
        }

        public interface SpaceCharFilter
        {
                public boolean isSpaceChar(int ch);
        }

    }
}    

