题解

#include <iostream>
#include<queue>
using namespace std;
int main(){
queue<int> q;
int n,m,p;
cin>>n;
for(int i=1;i<=n;i++){
cin>>m;
if(m1){
cin>>p;
q.push(p);
}else if(m2){
if(q.empty()){
cout<<"impossible!"<<endl;
}else{
//cout<<q.front()<<endl;
q.pop();
}
}else if(m==3){
if(q.empty()){
cout<<"impossible!"<<endl;
}else{
cout<<q.front()<<endl;
}

	}
}
return 0;

}