#include <bits/stdc++.h>
#define nmax 1000005

using namespace std;

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

int n;
int a[nmax];

int main()
{
    long long sol;
    int i;
    fin >> n;
    sol=0;
    for(i = 1; i <= n; i++)
        fin >> a[i];
    for(i = 1; i <= n; i++)
        if(a[i] > a[i - 1])
            sol += a[i] - a[i - 1];
    fout << sol;
    return 0;
}