Thread: Weird..?

Here's this program..could someone explain me where the function (mystery) is declared? i mean where is say that mystery returns a*b???

Code:

#include <stdio.h>
#include <stdlib.h>

int mystery( int a, int b ); /*function prototype*/

/*function main begins program execution*/
int main()
{
    int x;/*first integer*/
    int y;/*second integer*/
    
    printf("Enter two integers: ");
    scanf("%d %d", &x, &y);
    
    printf("The result is %d\n", mystery(x,y));
    
    system("pause");
    return 0; /*indicates succesful termination*/
    
} /*end main*/

/*Parameter b must be a positive integer
  to prevent infinite recursion */
  
int mystery( int a, int b )
{
    if ( b==1 )
    {
        return a;
    }
    else /*recursive step*/
    {
        return a + mystery( a, b-1 );
    }
}/*end function mystery*/

Thanks in advance!