#include <iostream>
#include <fstream>
#define NMAX 1000000

using namespace std;

ifstream f("operatii.in");
ofstream g("operatii.out");

int n;
long long sol, v[NMAX+10];

int main()
{
    f >> n;
    for(int i=1; i<=n; i++) f >> v[i];
    for(int i=1; i<=n; i++) sol = sol + max((long long)0, v[i] - v[i-1]);
    g << sol << '\n';
    return 0;
}