UVa 11313

#include<bits/stdc++.h>
using namespace std;

int main()
{
	int t;
	cin>>t;
	while(t--){
		int n,k,mod,mul,cnt=0;
		cin>>n>>k;
		while(n>=k){
			mod=n%k;
			mul=n/k;
			n=mul;
			n+=mod;
			cnt+=mul;

		}
		if(n==1){
			cout<<cnt<<endl;
		}
		else{
			cout<<"cannot do this"<<endl;
		}
	}
}