#include <iostream>
using namespace std;

int main() {
    freopen("operatii.in", "r", stdin);
    freopen("operatii.out", "w", stdout);
    
    int n, c, prev = 0;
    long long res = 0;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> c;
        if (c > prev) res += c - prev;
        prev = c;
    }
    cout << res;
    
    return 0;
}