text: #include <assert.h>
  #include <limits.h>
  #include <math.h>
  #include <stdbool.h>
  #include <stddef.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  char* readline();
  
  void print_table(int n) {
      for(int i = 1; i < 11; i++) 
          printf("%d x %d = %d\n", n, i, n * i);
  }
  
  int main()
  {
      char* n_endptr;
      char* n_str = readline();
      int n = strtol(n_str, &n_endptr, 10);
  
      if (n_endptr == n_str || *n_endptr != '\0') { exit(EXIT_FAILURE); }
      print_table(n);
      return 0;
  }
  
  char* readline() {
      size_t alloc_length = 1024;
      size_t data_length = 0;
      char* data = malloc(alloc_length);
  
      while (true) {
          char* cursor = data + data_length;
          char* line = fgets(cursor, alloc_length - data_length, stdin);
  
          if (!line) { break; }
  
          data_length += strlen(cursor);
  
          if (data_length < alloc_length - 1 || data[data_length - 1] == '\n') { break; }
  
          size_t new_length = alloc_length << 1;
          data = realloc(data, new_length);
  
          if (!data) { break; }
  
          alloc_length = new_length;
      }
  
      if (data[data_length - 1] == '\n') {
          data[data_length - 1] = '\0';
      }
  
      data = realloc(data, data_length);
  
      return data;
  }
  