https://umath.ru/theory/priznak-delimosti-na-7/

s = 0
k = 1
x = input()
while len(x) > 3:
    s += int(x[-3:]) * k
    k *= -1
    x = x[:-3]
s += int(x) * k
print(s % 7)

Edited by author 25.01.2019 02:16