// editor1
#include<stdio.h>
#include<math.h>

void main()
{
    int p,n,r;
    scanf("%d%d%d",&p,&r,&n);
    float rate=r/12
    double res1=p*rate*pow(1+rate,n);
    double res2=pow(1+rate,n)-1;
    double result=res1/res2;
    printf("%.2f",result);
    
}