#ifndef STACK_HPP

#define  STACK_SIZE 20

typedef struct {
   int data[STACK_SIZE];
   int top;
   int min;
}Stack;

void init( Stack *s );
void push( Stack *s, int val );
int pop( Stack *s );
bool full( Stack *s );
bool empty( Stack *s );
int min( Stack *s );

#endif

#include <iostream>
#include <cstdio>
#include <cstring>
#include "stack.hpp"

Stack assist;

void init( Stack *s )
{
   s->top = -1;
   s->min = -1;

   assist.top = -1;
}

void push( Stack *s ,int val )
{
   if( full(s) )
   {
      printf("%s\n", "stack is full");
      return;
   }
   if( (s->min == -1) || (val < s->min) )
   {
      s->min = val;
      assist.data[++assist.top] = val;
   }
   s->data[++s->top] = val;
}

int pop( Stack *s )
{
   int data;
   if( empty(s) )
   {
      printf( "%s\n", "stack is empty" );
      return -1;
   }
   data = s->data[s->top--];
   if( data == assist.data[assist.top] )
   {
      s->min = assist.data[--assist.top];
   }
   return data;
}

bool full( Stack *s )
{
   if( s->top == STACK_SIZE-1 )
   {
      return true;
   }
   return false;
}

bool empty( Stack *s )
{
   if( s->top == -1 )
   {
      return true;
   }
   return false;
}

int min( Stack *s )
{
   return s->min;
}

int main( int argc, char ** argv )
{
   Stack s;
   init( &s );
   push( &s, 3);
   std::cout << min( &s ) << std::endl;
   push( &s, 4);
   std::cout << min( &s ) << std::endl;
   push( &s, 2);
   std::cout << min( &s ) << std::endl;
   push( &s, 1);
   std::cout << min( &s ) << std::endl;
   pop( &s );
   std::cout << min( &s ) << std::endl;
   pop( &s );
   std::cout << min( &s ) << std::endl;
   push( &s, 0);
   std::cout << min( &s ) << std::endl;
   return 0;
}