cf 13a Numbers

#include <iostream>#include <cstdio>using namespace std;int gcd(int a,int b){    int t;    if(a<b)    {        t=a;a=b;b=t;    }    while(t=a%b)    {        a=b;b=t;    }    return b;}int main(){    int a,b=0,c;    scanf("%d",&a);    c=a-2;    for(int i=2;i<a;i++)    {        int t=a;        while(t)        {            int d=t%i;            b+=d;            t/=i;        }    }    int e=gcd(b,c);    printf("%d/%d\n",b/e,c/e);    return 0;}