03. Maximum and Minimum Element

#include <iostream>
#include <climits>
#include <stack>
#include <string>
#include <vector>
#include <sstream>
using namespace std;

int minimum(stack<int> buffer)
{
  int min = INT_MAX;

  while(buffer.size())
    {
      int top = buffer.top();
      buffer.pop();
      if(top < min)
        min = top;
    }
  return min;
}
int maximum(stack<int> buffer)
{
  int max = INT_MIN;

  while(buffer.size())
    {
      int top = buffer.top();
      buffer.pop();
      if(top > max)
        max = top;
    }
  return max;
}

int main()
{
  stack<int> buffer;
  int commands;
  cin >> commands;

  while(commands--)
    {
      int command, number;
      cin >> command;

      switch(command)
        {
          case 1:
           cin >> number;
           buffer.push(number);
           break;
          case 2:
          if(buffer.size())
            buffer.pop();
          break;
          case 3:
           if(buffer.size())
             cout << maximum(buffer) << endl;
           break;
          case 4:
           if(buffer.size())
            cout << minimum(buffer) << endl;
           break;
        }
    }

  while(buffer.size())
    {
      cout << buffer.top();
      buffer.pop();
      if(buffer.size())
        cout << ", ";
    }
  cout << endl;

  return 0;
}