#include <bits/stdc++.h>

using namespace std;
typedef long long LL;
const int N = 1000010;
int a[N];

LL ans;
int n;

//贪心法
int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i <= n; i++) if (a[i] > a[i - 1]) ans += a[i] - a[i - 1];
    cout << ans;
    return 0;
}