> #include <iostream.h>
> 
> int main(void){
> 	unsigned long long t, s, d;
> 	cin >> t;
> 	while(t--){
> 		cin>> s>>d;
> 		if(s<d)  cout<<"impossible"<<endl;
> 		else {
> 			if(s%2 ==0) cout <<(s/2+d/2)<<' '<<(s-d)/2<<endl;       <--- (s/2+d/2)<<应该为(s+d)/2,因为s和d可能同是奇数
> 			else cout <<((s-1)/2+(d+1)/2)<<' '<<(s-d)/2<< endl;
> 		}
> 	}
> 	return 0;
> }