#include <iostream>
#include <fstream>
#include <vector>

#define int long long

using namespace std;

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

const int N = 1e6 + 3;
int v[N];

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