#region Header
#!/usr/bin/env python3
# from typing import *

import sys
import io
import math
import collections
import decimal
import itertools
from queue import PriorityQueue
import bisect
import heapq

def input():
    return sys.stdin.readline()[:-1]

sys.setrecursionlimit(1000000)
#endregion

# _INPUT = """6
# 1 2 0 8 6 9
# """
# sys.stdin = io.StringIO(_INPUT)


def main():
    N = int(input()) + 1
    Y = [0] + list(map(int, input().split()))

    T = [Y[0]]
    for i in range(1, N):
        T.append(max(T[-1], Y[i]))

    dp = [[0 for _ in range(T[-1]+1)] for _ in range(N)]
    for i in range(1, N):
        for k in range(T[i]+1):
            if Y[i] <= k:
                dp[i][k] = min(dp[i-1][v] + (v - Y[i]) for v in range(Y[i], k+1))
            else:
                dp[i][k] = dp[i-1][k] + (Y[i] - k)
        for k in range(T[i]+1, T[-1]+1):
            dp[i][k] = dp[i][T[i]]

    v = min(dp[N-1])
    print(v)

if __name__ == '__main__':
    main()