hdu acm steps 2.1.4

#include<stdio.h>

int gcd(int a,int b)

{

return (b==0?a:gcd(b,a%b)); 

}

int main()

{

    int a,b,n,c,t;

    scanf("%d",&n);

    while(n--)

    {

        while(scanf("%d%d",&a,&b)==2)

        {

            c=b*2;

            while(gcd(a,c)!=b)

            {

                c+=b;                 

            }                        

                                     

            printf("%d\n",c);                           

        }

        

    }

    return 0;

}