#include <cstdio>
#define nmax 1000005
using namespace std;
long long sol;
int n,v[nmax];

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