#include <stdio.h>

#define FIN "operatii.in"
#define FOUT "operatii.out"

int N; long long Res;

int main(void)
{
    int i, prev, x;

    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);

    scanf("%d", &N);
    for (prev = i = 0; i < N; ++i)
    {
        scanf("%d", &x);
        if (prev < x) Res += x-prev;
        prev = x;
    }
    printf("%lld\n", Res);

    return 0;
}