题解

#include<bits/stdc++.h>
using namespace std;
int main() {
int m,n;
cin>>m>>n;
int diff=m-n;
double result;
if (diff<0){
result=(1<<(-diff));
}else{
result=1.0/(1<<diff);
}
cout<<fixed<< setprecision(7)<<result<<endl;
return 0;
}