no of pairs x^y greater than y^x

link="https://practice.geeksforgeeks.org/problems/number-of-pairs-1587115620/1#"
def countPairs(self,a,b,M,N):
        d=[0]*5
        for i in b:
            if i<5:d[i]+=1
        b=sorted(b)
        ans=0
        for i in a:
            if i==0:continue
            elif i==1:ans+=(d[0])
            else:
                idx=bisect.bisect_right(b,i)
                ans+=(len(b)-idx)
                ans+=(d[0]+d[1])
                if i==2:
                    ans-=(d[3]+d[4])
                elif i==3 :
                    ans+=(d[2])
        return ans