def Sum(s):
    Sum = 0
    for i in range(len(s)):
        Sum += int(s[i])
    return Sum

for n in range(4, 10_000):
    s = '5' + '2' * n
    while '52' in s or '2222' in s or '1122' in s:
        if '52' in s:
            s = s.replace('52', '11', 1)
        if '2222' in s:
            s = s.replace('2222', '5', 1)
        if '1122' in s:
            s = s.replace('1122', '25', 1)
    if Sum(s) % 10 == 7:
        print(n)
        break