#include <iostream>
using namespace std;
int ans;
int main()
{
    int n;
    scanf("%d",&n);
    int a[n+1];
    a[0] = 0;

    int Min = 1e9+7;
    for(int i=1;i<=n;i++)
    scanf("%d",&a[i]);

    for(int i=1;i<=n;i++)
    {
        if(a[i]-a[i-1] > 0)
        ans += a[i]-a[i-1];
    }
    cout<<ans;
    return 0;
}