#include <cstdio>

using namespace std;

int n, a, b;
long long sol;

int main()
{
    int i;
    freopen ("operatii.in", "r", stdin);
    freopen ("operatii.out", "w", stdout);
    scanf("%d", &n);
    for(i = 1; i <= n; ++i) {
        scanf("%d", &a);
        if(a > b)
            sol = sol + a - b;
        b = a;
    }
    printf("%lld\n", sol);
    return 0;
}