#include <fstream>

using namespace std;
ifstream in("operatii.in");
ofstream out("operatii.out");
int main()
{
    int n, ant=0, x;
    long long r=0;
    in>>n;
    for(int i=1; i<=n; i++)
    {
        in>>x;
        if(x>ant)
        {
            r+=x-ant;
        }
        ant=x;
    }
    out<<r;
}