Problem:
Score : 200 points

Problem Statement

You are given a string S of length N consisting of lowercase English letters.
We will cut this string at one position into two strings X and Y.
Here, we would like to maximize the number of different letters contained in both X and Y.
Find the largest possible number of different letters contained in both X and Y when we cut the string at the optimal position.

Constraints

2 \leq N \leq 100

|S| = N

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

N
S

Output

Print the largest possible number of different letters contained in both X and Y.

Sample Input 1

6
aabbca

Sample Output 1

2

If we cut the string between the third and fourth letters into X = aab and Y = bca, the letters contained in both X and Y are a and b.
There will never be three or more different letters contained in both X and Y, so the answer is 2.

Sample Input 2

10
aaaaaaaaaa

Sample Output 2

1

However we divide S, only a will be contained in both X and Y.

Sample Input 3

45
tgxgdqkyjzhyputjjtllptdfxocrylqfqjynmfbfucbir

Sample Output 3

9

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>
const int MAXN=300000;
int min(int x,int y)
{
    if(x>=y)
        return y;
    else
        return x;
}
int main()
{
    int n,i,j;
    int minn=MAXN;
    char a[MAXN];
    scanf("%d",&n);
    getchar();
    gets(a);
    for(i=0;i<n;i++)
    {
        int sum=0;
        for(j=0;j<i;j++)
        {
            if(a[j]=='W')
                sum+=1;
        }
        for(j=n-1;j>i;j--)
        {
            if(a[j]=='E')
              sum+=1;
        }
        minn=min(minn,sum);
    }
    printf("%d\n",minn);
    return 0;
}