A.书籍（book）

#include<bits/stdc++.h>
using namespace std;
stack<string> s;
string ss;
int q;
int main() {
    freopen("book.in","r",stdin);
    freopen("book.out","w",stdout);
    cin>>q;
    while(q--) {
        cin>>ss;
        if(ss=="READ") {
            cout<<s.top()<<endl;
            s.pop();
        } else
            s.push(ss);
    }
    return 0;
}