#include <stdio.h>

int i, j, k, n;
long long int sol;

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