prime

start_first_pair_value = int(input())
start_second_pair_value = int(input())
diff_first_pair = int(input())
diff_second_pair = int(input())
first_prime_pair = 0
second_prime_pair = 0
counter = 0
first_pair_found = False
second_pair_found = False

for first_pair in range(start_first_pair_value, ((start_first_pair_value + diff_first_pair) + 1)):
    for n in range(1, first_pair + 1):
        if first_pair % n == 0:
            counter += 1
    if counter <= 2:
        first_prime_pair = first_pair
        first_pair_found = True
    counter = 0
    for second_pair in range(start_second_pair_value, ((start_second_pair_value + diff_second_pair) + 1)):
        for n in range(1, second_pair + 1):
            if second_pair % n == 0:
                counter += 1
        if counter <= 2:
            second_prime_pair = second_pair
            second_pair_found = True
            if first_pair_found and second_pair_found:
                print(f"{first_prime_pair}{second_prime_pair}")
        counter = 0

    first_pair_found = False
    second_pair_found = False