#include <bits/stdc++.h>
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
int n;
unsigned long long rez;
int main()
{
    int i, curent, prev=0, dif;
    fin>>n;
    for(i=1; i<=n; i++)
    {
        fin>>curent;
        dif=curent-prev;
        if(dif>0) rez+=(unsigned long long)dif;
        prev=curent;
    }
    fout<<rez<<'\n';
    return 0;
}