#include <stdio.h>

/**
 * Hexadecimal number to integer
 */
static int c2n(int c) {
  return c - (c&64?:87:48);
}

int main(void) {
  char c;

  printf("Enter hexadecimal number: ");
  scanf("%c", &c);
  printf("%d\n", c2n(c));

  return 0;
}