#include <bits/stdc++.h>

using namespace std;

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

unsigned long long n ,anterior, x, operatii, i;

int main()
{
    fin>>n;
    anterior=0;
    for(i=1;i<=n;i++){
        fin>>x;
        if(x>anterior){
            operatii+=x-anterior;
        }
        anterior=x;
    }
    fout<<operatii;
    return 0;
}