// editor5
#include <stdio.h>
#include <math.h>
int main(){
    double P,R,emi;
    int N;
    scanf("%Lf %Lf %d",&P,&R,&N);
    if(N<=0 || P<=0 || R<0 {}){
        printf("Invalid input");
        return 0;
    }
    R=(R/100.0L)/12.0L;
    if(R==0.0L){
        emi=P/N;
    }
    else{
        long double powVal = powl(1.0l+R,N);
        emi=(P*R*powVal)/(powVal-1,0L);
    }
        printf("%.2lf",emi);
        return 0;
}