Even or Odd (practice problem)

This is not homework but it is supposed to be the third warm up before I actually begin the homework. I asked my lab instructor but he said to declare the function but i do not know what he is talking about. It stops when it hits the
Code:

` return ( even( n - 1 )); /* n is odd if and only n-1 is even`

I have deleted it, but when i do that the comp says everything is odd

Code:

` #include <stdio.h>`

int odd(int n)

{

if ( n == 1 ) /* if n is 1 then it is certainly true that it is odd */

return ( 1 );

else

return ( even( n - 1 )); /* n is odd if and only n-1 is even */

}

int even(int n)

{

if ( n == 0 ) /* if n is 0 then it is certainly true that it is even */

return ( 1 );

else

return ( odd( n - 1) ); /* n is even if and only n-1 is odd */

}

main()

{

int N;

printf("Please input a n integer.\n");

scanf("%d", &N);

if ( odd(N) )

printf("The number %d is odd.\n", N);

else

printf("The number %d is even.\n", N);

}