#include <stdio.h>

long tribonacci (int n) {
    if (n<2) return 0;
    else if (n==2) return 1;
    else return
          tribonacci(n-1)
        + tribonacci(n-2)
        + tribonacci(n-3);
}
int coil(int a) {
    if (a<=0)
        return 0;
    else return a + coil(a - 2);
}

double carpet(double field, int recursion) {
    if (recursion == 0) return field * 8.0/9.0;
    else return carpet(field * 8.0/9.0, recursion - 1);
}


int main(void) {
    int n;
    scanf("%d", &n);
    printf("%d\n", tribonacci(n));



    int a;
    scanf("%d", &a);
    printf("%d\n", coil(a));


    int recursion;
    double field;
    scanf("%d", &recursion);
    scanf("%lf", &field);

    printf("%d, %lf\n", recursion, field);

    printf("%lf\n", carpet(field, recursion));
}

#include <stdio.h>
#define SIZE 10


int ar[SIZE];
int top1 = -1;
int top2 = SIZE;

//Functions to push data
void push_stack1 (int data)
{
  if (top1 < top2 - 1)
  {
    ar[++top1] = data;
  }
  else
  {
    printf ("Stack Full! Cannot Push\n");
  }
}
void push_stack2 (int data)
{
  if (top1 < top2 - 1)
  {
    ar[--top2] = data;
  }
  else
  {
    printf ("Stack Full! Cannot Push\n");
  }
}

//Functions to pop data
void pop_stack1 ()
{
  if (top1 >= 0)
  {
    int popped_value = ar[top1--];
    printf ("%d is being popped from Stack 1\n", popped_value);
  }
  else
  {
    printf ("Stack Empty! Cannot Pop\n");
  }
}
void pop_stack2 ()
{
  if (top2 < SIZE)
  {
    int popped_value = ar[top2++];
    printf ("%d is being popped from Stack 2\n", popped_value);
  }
  else
  {
    printf ("Stack Empty! Cannot Pop\n");
  }
}

//Functions to Print Stack 1 and Stack 2
void print_stack1 ()
{
  int i;
  for (i = top1; i >= 0; --i)
  {
    printf ("%d ", ar[i]);
  }
  printf ("\n");
}
void print_stack2 ()
{
  int i;
  for (i = top2; i < SIZE; ++i)
  {
    printf ("%d ", ar[i]);
  }
  printf ("\n");
}

int main()
{
  int ar[SIZE];
  int i;
  int num_of_ele;

  printf ("We can push a total of 10 values\n");

  //Number of elements pushed in stack 1 is 6
  //Number of elements pushed in stack 2 is 4

  for (i = 1; i <= 6; ++i)
  {
    push_stack1 (i);
    printf ("Value Pushed in Stack 1 is %d\n", i);
  }
  for (i = 1; i <= 4; ++i)
  {
    push_stack2 (i);
    printf ("Value Pushed in Stack 2 is %d\n", i);
  }

  //Print Both Stacks
  print_stack1 ();
  print_stack2 ();

  //Pushing on Stack Full
  printf ("Pushing Value in Stack 1 is %d\n", 11);
  push_stack1 (11);

  //Popping All Elements From Stack 1
  num_of_ele = top1 + 1;
  while (num_of_ele)
  {
    pop_stack1 ();
    --num_of_ele;
  }

  //Trying to Pop From Empty Stack
  pop_stack1 ();

  return 0;
}

#include <stdio.h>

int MAXSIZE = 8;
int stack[8];
int top = -1;

int isempty() {

   if(top == -1)
      return 1;
   else
      return 0;
}

int isfull() {

   if(top == MAXSIZE)
      return 1;
   else
      return 0;
}

int peek() {
   return stack[top];
}

int pop() {
   int data;

   if(!isempty()) {
      data = stack[top];
      top = top - 1;
      return data;
   } else {
      printf("Could not retrieve data, Stack is empty.\n");
   }
}

int push(int data) {

   if(!isfull()) {
      top = top + 1;
      stack[top] = data;
   } else {
      printf("Could not insert data, Stack is full.\n");
   }
}

int main() {
   // push items on to the stack
   push(3);
   push(5);
   push(9);
   push(1);
   push(12);
   push(15);

   printf("Element at top of the stack: %d\n" ,peek());
   printf("Elements: \n");

   // print stack data
   while(!isempty()) {
      int data = pop();
      printf("%d\n",data);
   }

   printf("Stack full: %s\n" , isfull()?"true":"false");
   printf("Stack empty: %s\n" , isempty()?"true":"false");

   return 0;
}