CodeForces - 672B Different is Good （模拟）水

CodeForces - 672B

Different is Good

Time Limit: 2000MS Memory Limit: 262144KB 64bit IO Format: %I64d & %I64u

SubmitStatus

Description

A wise man told Kerem "Different is good" once, so Kerem wants all things in his life to be different.

Kerem recently got a string s consisting of lowercase English letters. Since Kerem likes it when things are different, he wants allsubstrings of his string s to be distinct. Substring is a string formed by some number of consecutive characters of the string. For example, string "aba" has substrings "" (empty substring), "a", "b", "a", "ab", "ba", "aba".

If string s has at least two equal substrings then Kerem will change characters at some positions to some other lowercase English letters. Changing characters is a very tiring job, so Kerem want to perform as few changes as possible.

Your task is to find the minimum number of changes needed to make all the substrings of the given string distinct, or determine that it is impossible.

Input

The first line of the input contains an integer n (1 ≤ n ≤ 100 000) — the length of the strings.

The second line contains the string s of lengthn consisting of only lowercase English letters.

Output

If it's impossible to change the string s such that all its substring are distinct print-1. Otherwise print the minimum required number of changes.

Sample Input

Input

2aa

Output

1

Input

4koko

Output

2

Input

5murat

Output

0

Sample Output

Hint

Source

Codeforces Round #352 (Div. 2)

//题意：

输入一个数n，再输入一个含有n个字符的字符串，问最少要改变几个字符可以使得所有的字符都不相同。

#include<stdio.h>#include<math.h>#include<string.h>#include<algorithm>#define N 100010using namespace std;char s[N];int vis[200];int main(){int n,cnt,i,j;while(scanf("%d",&n)!=EOF){memset(vis,0,sizeof(vis));cnt=0;scanf("%s",s);if(n>26)printf("-1\n");else{for(i=0;i<strlen(s);i++){if(vis[s[i]])cnt++;elsevis[s[i]]=1;}printf("%d\n",cnt);}}return 0;}