#define _GLIBCXX_FILESYSTEM
#include<bits/stdc++.h>
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
long long n, ant, crt, sol;
int main(){
    fin >> n;
    for(int i = 1; i <= n; i++){
        fin >> crt;
        if(crt > ant)
            sol += crt - ant;
        ant = crt;
    }
    fout << sol;
    return 0;
}