#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
    int n, h, h0 = 0, ans = 0;
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> h;
        if (h0 > h)
            ans += h0 - h;
        h0 = h;
    }
    ans += h;
    cout << ans << endl;
    return 0;
}