#include<iostream>
using namespace std;
class Calc{
    public:
    float add(float a,float b)
    {
        return a+b;
    }
    float sub(float a,float b)
    {
        return a-b;
    }
    float mul(float a,float b)
    {
        return a*b;
    }
    float divi(float a,float b)
    {
        return a/b;
    }
};
int main()
{
    Calc obj;
    int t;
    cin>>t;
    float a,b;
    cin>>a>>b;
    if(t==1)
    {
        cout<<obj.add(a,b);
    }
    else if(t==2)
    {
        cout<<obj.sub(a,b);
    }
    else if(t==3)
    {
        cout<<obj.mul(a,b);
    }
    else if(t==4)
    {
        if(b==0)
        {
            cout<<"Division by zero"<<endl;
        
    }
    else{
        cout<<obj.divi(a,b);
    }
    else
    {
        cout<<"Invalid input";
    }
    }
    return 0;
}