#include<stdio.h>

int main(){
    int p,r,n;
    scanf("%d %d %d",&p,&r,&n);
    if(n<=0){
        printf("Invalid input");
        return 0;
    }
    float num;
    int po;
    po=(1+r)**n;
    num=p * r * po;
    float den;
    den=po-1;
    float EMI=num/den;
    printf("%.2f",EMI);
    return 0;
}