CF520A.Pangram

A word or a sentence in some language is called a pangram if all the characters of the alphabet of this language appear in it at least once. Pangrams are often used to demonstrate fonts in printing or test the output devices.

You are given a string consisting of lowercase and uppercase Latin letters. Check whether this string is a pangram. We say that the string contains a letter of the Latin alphabet if this letter occurs in the string in uppercase or lowercase.

如果某个语言的单词或句子中至少包含该语言字母表中的所有字符各一次，则称其为“全字母句”（pangram）。全字母句常被用于印刷中展示字体，或测试输出设备。

给定一个仅由小写和大写拉丁字母组成的字符串。请判断该字符串是否为全字母句。我们称该字符串包含某个拉丁字母，当且仅当该字母（无论大小写）在字符串中至少出现一次。

The first line contains a single integer n (1 ≤ n ≤ 100) — the number of characters in the string.

The second line contains the string. The string consists only of uppercase and lowercase Latin letters.

第一行包含一个整数 $n$（$1 \leq n \leq 100$）—— 字符串中字符的个数。

第二行包含该字符串。字符串仅由大写和小写的拉丁字母组成。

Output "YES", if the string is a pangram and "NO" otherwise.

如果是全字母句（pangram），则输出 "YES"，否则输出 "NO"。