// editor3
#include<iostream>
using namespace std;

int main(){
    int operationtype;
    double num1, num2;
    
    cin>> operationtype;
    cin>> num1;
    cin>> num2;
    
    if(operationtype<=0){
        cout<<" Invalid input"
        return 0;
    }
    switch(operationtype){
        case 1:
        cout<<num1+num2;
        break;
        
        case 2:
        cout<<num1-num2;
        break;
        
        case 3:
        cout<<num1*num2;
        break;
       
       case 4:
       if(num2==0){
           cout<< "Division by zero";
       }
       else{
       cout<<num1/num2;
       }
       break;
       default:
       cout<< "Invalid input";
    }
    reeturn 0;
}