#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n];
  bool m = true;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  for (int i = 0; i < n - 2; i++) {
    if (a[i] + a[i + 1] > a[i + 2]) {
      m = false;
    }
  }
  if (m == true) {
    cout << "NO" << endl;
  } else {
    cout << "YES" << endl;
  }
  return 0;
}
