#include<iostream>
#define long long ll
using namespace std;
int main(){
	double n,m,x;
	cin>>n>>m>>x;
	double key=0;
	double low=1000;
	double mid=0;
	while(key=low-0.0001){
		mid=(key+low)/2;
		double high=n;
		for(int i=0;i<x;i++){
			high=high-m+high*(mid/100);
		}
		if(high>0.0001){
			low=mid;
		}else{
			key=mid;
		}
	}
	printf("%0.lf\n",(key*10)/10);
	return 0;
}