#include <bits/stdc++.h>
using namespace std;
void in(int *a, int n) {
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
}
int gcd(int a, int b) {
  if (b == 0)
    return a;
  else {
    return gcd(b, a % b);
  }
}
int primefac(int q) {
  int cnt = q, n = q;
  for (int i = 2; i < sqrt(q) + 1; i++) {
    while (q % i == 0) {
      q = q / i;
      cnt += n / i;
      n = n / i;
    }
  }
  if (q > 2) {
    cnt++;
  }
  return cnt;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ;
  int n, k = 8, an = 1;
  cin >> n;
  int a[n];
  in(a, n);
  sort(a, a + n);
  for (auto i = n - 2; i > 0; i--) {
    if (a[i - 1] > a[i + 1] - a[i]) k = 0;
  }
  if (k == 0)
    cout << "YES" << '\n';
  else
    cout << "NO" << '\n';
}
