题解 | #挑7#

count = 0
number = []
n = int(input())
for i in range(n):
    j = i+1
    if j % 7 == 0:
        count += 1
        number.append(j)
    else:
        for k in str(j):
            if (k == '7') and (j not in number):
                count += 1
                number.append(j)

print(count)

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