#include<iostream>
#include<math>
using namespace std;
float area(float side){
    if(side<0||side>1000)
     return -1;
    return side*side;
}
float area(float len,float width){
    if(len<0||width<0||len>1000||width>1000)
     return-1;
    return len*width;
}
float area(double radius){
    if(radius<0||radius>1000)
     return-1;
    return M_PI*radius*radius>1000)
}
int main(){
    int t;
    cin>>t;
switch(t){
    case 1:{
        float side;
        cin>>side;
        float a=area(side);
        if(a<0)
         cout<<"Invalid input";
        else
         cout<<a;
         break;
    case 2:{
        float lenght,width;
        cin>>lenght>>width;
        float a=area(lenght,width);
        if(a<0)
         cout<<"Invalid input";
        else
         cout<<a;
         break;
    }
    case 3:{
        double radius;
        cin>>radius:
        float a=area(radius);
        if(a,0)
         cout<<"Invalid input";
        else cout<<a;
        break;
    }
    default:
    cout<<"Invalid input"
}
return 0;
}