#!/usr/bin/env python3

def main(m, lim=10**7):
    for n, p in enumerate(primes(lim), 1):
        r = ((2*n)%p)*p if n%2 else 2
        if r > m:
            return n, p, r
    return False

def primes(n):
    sieve = [True]*n
    for p in range(2, len(sieve)):
        if not sieve[p]:
            continue
        for i in range(2*p, len(sieve), p):
            sieve[i] = False
        yield p

#print(main(10**9, 10**6))
print(main(10**10, 10**6)[0])