Deepak and primes 2 wrong ans

#1

im getting wrong ans in many test cases.
whats wrong in this https://ide.codingblocks.com/#/s/23836
ques link https://hack.codingblocks.com/contests/c/473/760

#2

Use segmented sieve instead of normal sieve

#3

i have used normal sieve to find prime from 1 to sqrt(b) and then used segmented sieve.
whats wrong in it