I used Mo's algo to solve this problem .

First compare function: It gives me wrong answer Submission1

bool comp(query &a,query &b)
{
 int x=a.L/bsize;
 int y=b.L/bsize;
 
 if(x!=y)
 return x<y;
 if(x&1)
 return (a.R > b.R);
 else
 return (a.R < b.R);
}

Second function : Gives me AC Submission2

bool comp(query &a,query &b)
{
 int x=a.L/bsize;
 int y=b.L/bsize;
 
 if(x!=y)
 return x<y;
 else
 return a.R < b.R;
}

First one is an optimisation,but not able to find why it gives wrong answer