#include <fstream>

using namespace std;

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

const int NMAX = 1000000;

int main() {
    long long N, Ans = 0, last = 0, elem;
    in >> N;
    for( int i = 1;  i <= N;  ++i ) {
        in >> elem;
        Ans += max( elem-last, 0LL );
        last = elem;
    }
    out << Ans << '\n';
    return 0;
}