#include <iostream>
#include <cstdlib>
#include <ctime>

struct TStack
{
   int value;
   TStack* next;
};

//-----------------------------------------------------------------------------
TStack* Push(TStack*& stack, int value)
{
   TStack* node = new TStack;
   node->value = value;
   node->next = stack;

   stack = node;

   return stack;
}
//-----------------------------------------------------------------------------
void Clear(TStack*& stack)
{
   TStack* node;

   while (stack)
   {
      node = stack;
      stack = stack->next;
      delete node;
   }
}
//-----------------------------------------------------------------------------
bool IsNegative(int value)
{
   return (value < 0);
}
//-----------------------------------------------------------------------------
TStack*& FindElement(TStack*& stack, bool func(int))
{
   if (stack && !func(stack->value))
   {
      return FindElement(stack->next, func);
   }

   return stack;
}
//-----------------------------------------------------------------------------
TStack* DeleteFirstNegative(TStack*& stack)
{
   TStack*& find = FindElement(stack, IsNegative);

   if (find)
   {
      TStack* node = find;
      find = find->next;

      delete node;
   }

   return stack;
}
//-----------------------------------------------------------------------------
int Random(int min, int max)
{
   return (rand() % (max - min) + min);
}
//-----------------------------------------------------------------------------
TStack* GetGenStack(size_t count, int min, int max)
{
   TStack* stack = NULL;

   while (count--)
   {
      Push(stack, Random(min, max));
   }

   return stack;
}
//-----------------------------------------------------------------------------
std::ostream& operator << (std::ostream& out, const TStack* stack)
{
   for (; stack; stack = stack->next)
   {
      out << stack->value << " ";
   }

   return out;
}
//-----------------------------------------------------------------------------

int main()
{
   srand(time(NULL));

   TStack* stack = GetGenStack(10, -10, 10);

   std::cout << "source: " << stack << std::endl;

   DeleteFirstNegative(stack);

   std::cout << "result: " << stack << std::endl;

   Clear(stack);

   return 0;
}

source: 0 -5 6 3 -4 -10 -2 -9 3 9 
result: 0 6 3 -4 -10 -2 -9 3 9