#include <bits/stdc++.h>
#define int long long 
using namespace std;

signed main() {
    ifstream cin("operatii.in");
    ofstream cout("operatii.out");
    
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int n; cin >> n;
    vector<int> a(n);

    int last = 0;
    int ans = 0;

    for(int i = 0; i < n; i ++) {
        cin >> a[i];
        if(a[i] > last)
            ans += a[i] - last;
        last = a[i];
    }

    cout << ans;
}