#include <bits/stdc++.h>
using namespace std;
typedef long long i64;

const int NMAX = 1000005;

int main(void) {
    freopen("operatii.in", "r", stdin);
    freopen("operatii.out", "w", stdout);
    int n, a, b;
    i64 ans;

    a   = 0;
    ans = 0;

    scanf("%d",&n);
    for(int i=1; i<=n; ++i) {
        scanf("%d",&b);
        ans+= max(0, b-a);
        a = b;
    }

    printf("%lld",ans);

    fclose(stdin);
    fclose(stdout);
    return 0;
}