#include<iostream>
using namespace std;
long V,T,P;
main()
{
	cin>>V>>T>>P;
	++P;
	long L=V*P,R=V*P*3;
	while(R-L>1)
	{
		long M=L+R>>1;
		if((M+T-1)/T+V*P<M)R=M;
		else L=M;
	}
	cout<<L<<endl;
}