Stacks on stacks (implement a program that reads in push, pop, and inc operations, output the top of the stack at the end of each operation, prevent errors)

stackitup.cc

#include <iostream>
#include <stack>
#include <vector>
using namespace std;

int main() {
  string s;
  stack<int> st;
  while (cin >> s) {
    int i;
    if (s == "push") {
      cin >> i;
      st.push(i);
    } else if (s == "pop") {
      if (!st.empty()) {
        st.pop();
      }
    } else if (s == "inc") {
      int x, d;
      cin >> x;
      cin >> d;

      // add d to the top x elements in the stack
      stack<int> tmp;
      while (!st.empty() && x > 0) {
        tmp.push(st.top() + d);
        st.pop();
        --x;
      }
      while (!tmp.empty()) {
        st.push(tmp.top());
        tmp.pop();
      }
    }

    if (st.empty()) {
      cout << "EMPTY" << endl;
    } else {
      cout << st.top() << endl;
    }
  }
  return 0;
}