Avin has a string. He would like to uniform-randomly select four characters (selecting the same character is allowed) from it. You are asked to calculate the probability of the four characters being ”avin” in order.

Input

The first line contains n (1 ≤ n ≤ 100), the length of the string. The second line contains the string. To simplify the problem, the characters of the string are from ’a’, ’v’, ’i’, ’n’.

Output

Print the reduced fraction (the greatest common divisor of the numerator and denominator is 1), representing the probability. If the answer is 0, you should output “0/1”.

Sample Input

4
avin
4
aaaa

Sample Output

1/256
0/1

這道題真的超簡單，結果在定義的時候著急了，馬虎了，找了好久的錯誤才找到。

#include"stdio.h" #include"math.h" int gcd(int o,int p) {return p==0?o:gcd(p,o%p);} int main() {int n;char a[150];int x;while(~scanf("%d",&n)){int sum=1;int sum1=0;int sum2=0;int sum3=0;int sum4=0;scanf("%s",a);for(int i=0;i<n;i++){if(a[i]=='a'){sum1++;}if(a[i]=='v'){sum2++;}if(a[i]=='i'){sum3++;}if(a[i]=='n'){sum4++;}}for(int i=0;i<4;i++){sum=sum*n;}x=sum1*sum2*sum3*sum4;if(x!=0){if(gcd!=0){printf("%d/%d\n",x/gcd(x,sum),sum/gcd(x,sum));}else{printf("%d/%d\n",x,sum);}}else{printf("0/1\n");}}return 0; }

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