#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
using namespace std;
int main(){
int a,b,c;
double s,area;
scanf("%d %d %d",&a,&b,&c);
if(a+b<c||a+c<b||b+c<a){
printf("Impossible");
}
else{
s=(a+b+c)/2;
area=sqrt(s*(s-a)*(s-b)*(s-c));
printf("%.3lf",area);
}
return 0;
}