Deepak and primes

#1

can you please give me a hint how to approach the problem as the constraints are huge .how will we know that upto what value should we iterate to get 500000th prime number

#2

@sjduttabbsr2017
You have to iterate till n = 1e8;
Its just a rough estimate, because you can at most do ~1e8 in 1 sec. and 1e8 works for 500000th prime number.

#3

But we can only build the array or vector upto size 1e6 .how can we iterate till 1e8.Also iterating till 1e6 doesnot give 5000000 th prime number.