import sys

b, d, a = map(int, input().split())

try:
    best_d = min(b*f for f in range(1, 11) if (b*f) % 10 == d)
except ValueError:
    print(0)
    sys.exit(0)

best_0 = min(b*f for f in range(1, 11) if (b*f) % 10 == 0)

ans = 1

while best_d <= a:
    assert best_d % 10 == d
    assert best_0 % 10 == 0
    best_d //= 10  # Drop trailing d
    best_0 //= 10  # Drop trailing zero

    if a % 10 >= d:
        a = a // 10
    else:
        a = a // 10 - 1

    try:
        best_d = min(best_d + f * best_0 for f in range(11) if (best_d + f * best_0) % 10 == d)
    except ValueError:
        print(ans)
        sys.exit(0)
    best_0 = min(f * best_0 for f in range(1, 11) if (f * best_0) % 10 == 0)
    ans += 1

print(ans-1)