#include<stdio.h>

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