#include <bits/stdc++.h>
#define int long long

using namespace std;

ifstream fin ("operatii.in");
ofstream fout ("operatii.out");

int v[1000005];

signed main()
{
    int n;
    fin >> n;
    for (int i=1;i<=n;++i){
        fin >> v[i];
    }
    int ans = 0;
    for (int i=1;i<=n;++i){
        if (v[i]<=v[i-1]) continue;
        ans += v[i]-v[i-1];
    }
    fout << ans;
    return 0;
}