F. Primes in Intervaltime limit per test2 secondsmemory limit per test64 megabytesinputstandard inputoutputstandard outputYou are given two integers a and b (a ≤ b). How many prime numbers are there on the interval from a to b, inclusive?InputThe input contains two integers a and b (2 ≤ a ≤ b ≤ 1 000 000), separated by a single space.OutputOutput a single integer — the number of primes between a and b, inclusive.ExamplesInput10 20Output4Input23 23Output1Input271 566Output46
Input10 20
Output4
['*special problem', '*1900']