CodeForces 13A - Numbers

#include <iostream>
#include <cstdio>
using namespace std;
int gcd(int a,int b)
{
return b==0?a:gcd(b,a%b);
}
int main()
{
int n;
cin>>n;
int sum=0;
for(int i=2;i<=n-1;++i)
{
int tmp=n;
while(tmp!=0)
{
sum+=(tmp%i);
tmp/=i;
}
}
int c=gcd(sum,n-2);
printf("%d/%d",sum/c,(n-2)/c);
return 0;
}