# エラトステネスの篩

def make_prime_table(n):

    sieve = list(range(n + 1))

    sieve[0] = -1

    sieve[1] = -1

    for i in range(2, int(n ** 0.5) + 1):

        if sieve[i] != i:

            continue

        for j in range(i * i, n + 1, i):

            if sieve[j] == j:

                sieve[j] = i

    return sieve





X = int(eval(input()))



N = 10 ** 6

prime_table = make_prime_table(N)

for i in range(X, N + 1):

    if prime_table[i] == i:

        print(i)

        break

def make_prime_table(n):

    sieve = list(range(n + 1))

    sieve[0] = -1

    sieve[1] = -1

    for i in range(4, n + 1, 2):

        sieve[i] = 2

    for i in range(3, int(n ** 0.5) + 1, 2):

        if sieve[i] != i:

            continue

        for j in range(i * i, n + 1, i * 2):

            if sieve[j] == j:

                sieve[j] = i

    return sieve



X = int(eval(input()))



N = 10 ** 6

prime_table = make_prime_table(N)

for i in range(X, N + 1):

    if prime_table[i] == i:

        print(i)

        break

# エラトステネスの篩
def make_prime_table(n):
    sieve = list(range(n + 1))
    sieve[0] = -1
    sieve[1] = -1
    for i in range(2, int(n**0.5) + 1):
        if sieve[i] != i:
            continue
        for j in range(i * i, n + 1, i):
            if sieve[j] == j:
                sieve[j] = i
    return sieve


X = int(eval(input()))
N = 10**6
prime_table = make_prime_table(N)
for i in range(X, N + 1):
    if prime_table[i] == i:
        print(i)
        break

def make_prime_table(n):
    sieve = list(range(n + 1))
    sieve[0] = -1
    sieve[1] = -1
    for i in range(4, n + 1, 2):
        sieve[i] = 2
    for i in range(3, int(n**0.5) + 1, 2):
        if sieve[i] != i:
            continue
        for j in range(i * i, n + 1, i * 2):
            if sieve[j] == j:
                sieve[j] = i
    return sieve


X = int(eval(input()))
N = 10**6
prime_table = make_prime_table(N)
for i in range(X, N + 1):
    if prime_table[i] == i:
        print(i)
        break

-# エラトステネスの篩 -    for i in range(2, int(n**0.5) + 1): +    for i in range(4, n + 1, 2): +        sieve[i] = 2 +    for i in range(3, int(n**0.5) + 1, 2): -        for j in range(i * i, n + 1, i): +        for j in range(i * i, n + 1, i * 2):