#include<iostream>
using namespace std;
int main(){
setlocale(LC_ALL, "rus");
float a, b;
cout<<"write a & b"<<endl;
cin>>a>>b;
cout<<"a+b="<<a+b<<endl;
cout<<"a-b="<<a-b<<endl;
cout<<"a*b="<<a*b<<endl;
try{
if(b==0){
throw "dev on 0" ;
}
cout<<"a/b="<<a/b<<endl;
}
catch(char const*str){
cout<<str<<endl;
}
}