#include <stdio.h>
#define SIZE 100

typedef struct stack {
  int top;
  int capacity;
  int* array;
} stack;

void push(stack* st, int val) {
  st->array[++st->top] = val;
}

void pop(stack* st) {
  st->top--;
}

int peek(stack* st) {
  return st->array[st->top];
}

int main(void) {
  char input[SIZE];
  
  fscanf(input, SIZE, stdin);
}