#include <bits/stdc++.h>
using namespace std;
double a,b;
int main()
{
cin>>a>>b;
cout<<"a truoc khi doi la:"<<fixed<<setprecision(2)<<a<<endl;
cout<<"b truoc khi doi la:"<<fixed<<setprecision(2)<<b<<endl;
swap(a,b);
cout<<"a sau khi doi la:"<<fixed<<setprecision(2)<<a<<endl;
cout<<"b sau khi doi la:"<<fixed<<setprecision(2)<<b;
return 0;
}