Write a c program to find GCD of two/three numbers using recursion?

#include<stdio.h> 
#include<conio.h> 

int GCD (int a,int b) 
{ 
if (a<0) 

a= -a; 
if (b<0) 

b= -b; 
if (a==0 || b==1 || a==b) 

return b; 
if (a==1 || b==0) 

return a; 
if (a>b) 

return GCD (b, a%b); 
else

 return GCD (a, b%a); 
} 

void main() 
{ 
int x,y; 
clrscr(); 
printf("nEnter 1st number:"); 
scanf("%d",&x); 
printf("nEnter 2nd number:"); 
scanf("%d",&y); 
printf("\nGCD is:%d", GCD(x,y)); 
getch(); 
} 



And for three number: 

int GCD3 (int x,int y, int z) 
{ 
return GCD(x,GCD(y,z)); 
}