Halp

Beginner Cfag here, what am I doing wrong? I keep segfaulting.

(Unused ints are there for when I write the fight function. The dumb math stuff is just there because I am a beginner and try to do every function I can as much as possible, to drum it into me.)

/* hello.c: A simple program to learn the basics of C */
#include <stdio.h>

int main()
{
  int a;
  int b;
  int a_hp;
  int b_hp;
  int a_atkpwr;
  int b_atkpwr;
  int a_acracy;
  int b_acracy;
  char skill;

  printf( "Enter an integer\n" );
  scanf( "%d", &a );
  printf( "You entered %d\nAdd 5 to this number, and enter the result.\n", a );
  b = a + 5 ;
  scanf( "%d", &a );
  if ( a == b )
    {
      printf( "Correct.\n" );
      printf( "Now divide the number by 5 (Rounded).\n" );
      b = a / 5;
      scanf( "%d", &a );
      if ( a == b )
    {
      printf( "Correct. Now, let's play a game.\n" );
      printf( "Would you like your character to be strength or skill-based? Enter ``str'', without quotes, for strngth, and ``ski'', without quotes, for skill.\n" );
      printf( "Skill-based players have more health, but strength-based players have more attack.\n");
      printf( "Both are useful with different types of attack.\n" );
      scanf( "%s", &skill );
      if ( strcmp( skill, "str" ) == 0 )
        {
          a_atkpwr = 10;
          printf( "Your character is STRONG.\n" );
        }
      else if ( strcmp( skill, "ski" ) == 0 )
        {
          a_atkpwr = 5;
          printf( "Your character is SKILLFUL.\n" );
        }
      else
        {
          printf( "Please re-read the instructions and try again.\n" );
        }
    }
      else
    {
      printf( "No. Now you may not play the game.\n" );
    }
    }
  else
    {
      printf( "Incorrect.\n" );
    }
  getchar();
  return 0;
}

You know, every time your program segfaults, you start your local gdb and find out where, why, and when it crashes. Then you fix the problems. Easy, isn't it?