#include<stdio.h>
int main(){
    int  P,R,N,result;
    float  emi;
    scanf("%d %d %d",&P,&R,&N);
    if(N==0){
        printf("Invalid input");
    }
    
    result= pow((1+R),N);
    emi = P*R*result/(result-1);
    printf("%.2",emi)
}