#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

using namespace std;

int inf=1e9;

int a,b,n;

double ans=inf,s;

double dfs(double x,double y,int cnt)

{

//    printf("x=%.2lf y=%.2lf cnt=%d\n",x,y,cnt);

    if(x<y)swap(x,y);

    double ret=inf;

    if(cnt==)return x/y;

    for(int i=;i<cnt;i++)

    {

//        double k=(x*y-i*s)/y;

        double k=x*i/cnt;

        ret=min(ret,max(dfs(k,y,i),dfs(x-k,y,cnt-i)));

//        k=(x*y-i*s)/x;

        k=y*i/cnt;

        ret=min(ret,max(dfs(x,k,i),dfs(x,y-k,cnt-i)));

    }

    return ret;

}

int main()

{

    scanf("%d%d%d",&a,&b,&n);

    s=1.0*a*b/n;

    if(a<b)swap(a,b);

//    for(int i=1;i<n;i++)

//    {

//        double k=(1.0*a*b-i*s)/b;

//        ans=min(ans,max(dfs(k,b,n-i),dfs(a-k,b,i)));

//    }

    printf("%.6lf",dfs(a,b,n));

    return ;

}