// editor1
#include<iostream>
using namespace std;
class circle{
    private:
    float radius;
    public:
    circle(float r){
        radius = r;
    }
    boll isvalid(){
        return(radius > 0 && radius <= 1000);
        
    }
    float getCircumference(){
        return 2 * 3.14159 * radius;
    }
};
int main(){
    float r;
    cin >> r; 
    circle c(r);
    if(!c.isValid()){
        cout << " Invalid input"<< endl;
        
    }
    return 0;
}