#include <stdio.h>
int n;
long long rez;
int main ()
{
    freopen ("operatii.in","r",stdin);
    freopen ("operatii.out","w",stdout);
    int i,cur,prec=0;
    scanf ("%d",&n);
    for (i=1; i<=n; ++i)
    {
        scanf ("%d",&cur);
        if (cur>prec)
            rez+=cur-prec;
        prec=cur;
    }
    printf ("%lld",rez);
    return 0;
}