Long Multiply

#define LL long long int
LL multiply(LL a, LL b)
  {
       if(b==0)return 0;
       if(b==1)return a;
       LL c=multiply(a,b/2);
       c=(c+c)%m;
       if(b%2!=0)c=(temp+a)%m;
       return c;   
  }