Untitled

#include <string>
#include <iostream>
#include<stdlib.h>
using namespace std;
int main()
{
	int n;
	cin >> n;
	string a;
	cin >> a;
	int s = 0;
	int i;
	for (i = 0; i < a.size(); i++)
	{
		a[i] = tolower(a[i]);
	}
	for (int i = 0; i < a.size(); i++)
	{
		for (int j = i + 1; j < a.size(); j++)
		{
			if (a[i] == a[j]) a[i] = ' ';
		}
	}
	for (int i = 0; i < a.size(); i++)
	{
		if (a[i] != ' ')s++;
	}
	if (26 == s) cout << "YES";
	else cout << "NO";
}