Untitled

#include <iostream>
#include <fstream>
#include <vector>
#include <string>
using namespace std;
struct a {
	int h = 0;
	char l;
};
int main(){
	int flag = 0;
	int len;
	cin >> len;
	string h;
	cin >> h;
	a mas[52];
	for (int i = 0; i < 26; i++){
		mas[i].l = char(65+i);
	}
	for (int i = 0; i < 26; i++) {
		mas[i+26].l = char(97 + i);
	}
	if (len >= 26) {
		for (int i = 0; i < len; i++) {
			for (int j = 0; j < 26; j++) {
				if (h[i] == mas[j].l || h[i] == mas[j + 26].l) {
					mas[j].h = 1;
				}
			}
		}
		for (int i = 0; i < 26; i++){
			if (mas[i].h == 1) continue;
			else {
				flag = 1;
				break;
			}
		}
		if (!flag) cout << "YES";
		else cout << "NO";
	}
	else cout << "NO";
}