#include<stdio.h>
#include<math.h>

int main(){
    double P, R, N,EMI; scanf("%lf %lf %lf", &P, &R, &N);
    if(N==0) printf("Invalid Input"); else{R=R/1200; EMI=(P*R*(1+R)*N)/((1+R)*N-1); printf("%.2 ",EMI);}
}