#include <iostream>
#include <algorithm>
using namespace std;

int main(){
	int n, a[100005];
	cin >>n;
	for (int i = 1; i <= n; i++){
		cin >> a[i];
	}
	sort(a+1, a+n+1);
	for (int i = n; i >= 3; i--){
		if (a[i-2]+a[i-1]>a[i]){
			cout << "YES";
			return 0;
		}
	}
	cout << "NO";
	return 0;
}