POJ 2509

 #include <iostream>
 #include <stdio.h>
 using namespace std;

 int main()
 {
     //freopen("acm.acm","r",stdin);
     int n;
     int k;
     int sum;
     int mod;
     int tem;
     while(cin>>n>>k)
     {
         sum = ;
         while(n >= k)
         {
             mod = n % k;
             tem = n / k;
             sum += n - mod;
             n = mod + tem;
         }
         sum += mod + tem;
         cout<<sum<<endl;

     }
 }