Comment body goes here.

Just use basic mathematics.

Let take example a=12,b=14;

what do we do in maths,divide large number by small number and take remainder.

The same thing is also happening here.

code is

int gcd(int a,int b)

{

if(b==0)

return a; //bcz if one number is zero then gcd is other number.

return gcd(b,a%b);

}