#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
using namespace std;

#define MAX 52

map<string, int> mp;

int n;


priority_queue<pair<int,string> > q;

int main(){
	cin >> n;
	for (int i = 0; i < n; i++){
		string a;
		cin >> a;
		mp[a]++;
	}
	for (auto it = mp.begin(); it != mp.end(); it++){
		q.push(make_pair((*it).second, (*it).first));
	}
	string emp = "q";
	while (!q.empty()){
		pair<int, string> a = q.top();
		q.pop();
		if (a.second == emp){
			if (q.empty()){
				puts("NO");
				return 0;
			}
			pair<int, string> tmp = q.top();
			q.pop();
			q.push(a);
			a = tmp;
		}
		emp = a.second;
		a.first--;
		if (a.first){
			q.push(a);
		}
	}
	puts("YES");
	return 0;
}