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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int main() {
  4.     int a; cin >> a;
  5.     stack<int> s;
  6.     while (a--) {
  7.         int b; cin >> b;
  8.         if (b == 1) {
  9.             int c; cin >> c;
  10.             s.push(c);
  11.         } else if (b == 2) {
  12.             if (!s.empty()) s.pop();
  13.         } else {
  14.             if (s.empty()) cout << -1 << "\n";
  15.             else cout << s.top() << "\n";
  16.         }
  17.     }
  18. }
  19.  
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin 
8
1 2
1 3
2
3
2
3
1 5
3
stdout 
2
-1
5
https://ideone.com/bivBsO
language:
C++ (gcc 8.3)
created:
4 days ago
visibility:
public

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