#include<iostream>
#include<vector>

using namespace std;

int n, a = 0, b = 0, c = 0;
vector<int> v;

bool Sum(int k)
{
	b += ((v[k] + 1) * (v[k] + 1)) - (v[k] * v[k]);
	c += ((v[k] - 1) * (v[k] - 1)) - (v[k] * v[k]);
	return ((a + 1) * (a + 1) == b || (a - 1) * (a - 1) == c);
}

int main()
{
	cin >> n;
	v.resize(n);
	for (int i = 0; i < n; ++i)
	{
		cin >> v[i];
		a += v[i];
		b += v[i] * v[i];
	}
	c = b;
	for (int i = 0; i < n; ++i)
	if (Sum(i))
	{
		cout << "YES" << endl;
		return 0;
	}
	cout << "NO" << endl;
	return 0;
}