# include <stdlib.h>
# include <cstdio>

using namespace std;

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