#include <cstdio>
#include <algorithm>
using namespace std;
int v[1000001];
int main()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
    int ok,n,i;
    scanf("%d",&n);
    long long s = 0;
    for(i=1;i<=n;i++)
    {
        scanf("%d",&v[i]);
        s += max (0, v[i] - v[i - 1]);
    }

    printf("%lld\n",s);
    return 0;
}