#include<iostream>
#include<string>
#include<algorithm>
#include<functional>
#include<vector>
#include<set>
#include<queue>
#include<list>
#include<stdio.h>
#include<stdlib.h>
#include<map>

#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()

typedef long long ll;

using namespace std;

int main() {

	int n;
	cin >> n;

	if (n == 1) {
		cout << "NO" << endl;
		return 0;
	}

	map<string, int> a;

	for (int i = 0; i < n; i++) {
		string buf;
		cin >> buf;

		++a[buf];
	}

	fore(i, a) {

		if (i.second >= n - 1) {
			cout << "NO" << endl;
			return 0;
		}
	}

	cout << "YES" << endl;
}