#include <iostream>

using namespace std;

const int N = 1e5 + 10;

int n, res, w[N];

int main() {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) scanf("%d",w + i);

    for (int i = 2; i <= n; i++) 
        if (w[i] > w[i-1]) 
           res += w[i] - w[i-1];

    printf("%d\n", res);
    return 0;
}