#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
const int mod = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  int arr[n + 2];
  long long energy = 0, ans = 0;
  arr[0] = 0;
  for (int i = 1; i <= n; i++) {
    cin >> arr[i];
  }
  for (int i = 0; i < n; i++) {
    if (arr[i] - arr[i + 1] < 0) {
      int temp = arr[i + 1] - arr[i];
      if (energy >= temp) {
        energy -= temp;
      } else {
        ans += (temp - energy);
        energy = 0;
      }
    } else {
      energy += abs(arr[i] - arr[i + 1]);
    }
  }
  cout << ans << endl;
}
