#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
double n,s,m;
double read()
{
    ,f=; char ch=getchar();
    ;ch=getchar();}
    +ch-',ch=getchar();
    return x*f;
}
int pd(double x,int tot,double sum)
{
    &&tot<=m) ;
    ;
    pd(x,tot+,sum*(+x)-s);
}
int check(double x)
{
    ,n)) ;
    ;
}
int main()
{
    n=read(),s=read(),m=read();
    ,r=,mid,ans;
    while(r-l>=0.000001)
    {
        mid=(l+r)/;
        if(check(mid)) ans=mid,l=mid;
        else r=mid;
    }
    ans*=;
    printf("%.1lf",ans);
    ;
}