#include <fstream>

using namespace std ;

const int NMAX = 1000005 ;

ifstream cin("operatii.in") ;
ofstream cout("operatii.out") ;


long long N, X, P, R ;
long long V[NMAX] ;

int main()
{
        cin >> P ;
        for(int i = 1 ;i <= P ; ++ i)
        {
            cin >> N ;
            X < N ? R = R + N - X : R ;
            X = N;
        }

        cout << R << '\n' ;

    cin.close() ;
    cout.close() ;
    return 0 ;
}