TBC1237 C++

#include <bits/stdc++.h>
using namespace std;
string s;
long long a=1,b;
void giai()
{
    bool ok=false; 
   for(int i=0;i<s.length();i++)
   {
         if(ok)
         {
             b+=(int)(s[i])-48; b*=10;
             a*=10;
      }
      if(s[i]=='.') ok =true;
   }
   b/=10;
   cout<<a/__gcd(a,b);
}
int main()
{
    ios_base::sync_with_stdio(0);
    cout.tie(0); cin.tie(0);
    freopen("tbc1237.inp","r",stdin);
    freopen("tbc1237.out","w",stdout);
    cin>>s;
    giai();
}