#include <bits/stdc++.h>

using namespace std;
ifstream in("operatii.in");
ofstream out("operatii.out");


int main()
{
    int n, prev=0;
    long long cnt = 0;
    in >> n;
    for (int i = 1; i<=n; i++)
    {
        int x;
        in >> x;
        cnt+=max(0,x-prev);
        prev = x;
    }
    out << cnt;
}