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  • CF 152 B. Chilly Willy

    B. Chilly Willy
    time limit per test
    2 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Chilly Willy loves playing with numbers. He only knows prime numbers that are digits yet. These numbers are 2, 3, 5 and 7. But Willy grew rather bored of such numbers, so he came up with a few games that were connected with them.

    Chilly Willy wants to find the minimum number of length n, such that it is simultaneously divisible by all numbers Willy already knows (2, 3, 5 and 7). Help him with that.

    A number's length is the number of digits in its decimal representation without leading zeros.

    Input

    A single input line contains a single integer n (1 ≤ n ≤ 105).

    Output

    Print a single integer — the answer to the problem without leading zeroes, or "-1" (without the quotes), if the number that meet the problem condition does not exist.

    Sample test(s)
    Input
    1
    Output
    -1
    Input
    5
    Output
    10080




    水题,找到它的周期就好了。
    n==1||n==2输出-1,至少210.
    n==3 210.


    然后后面就是以六个数为一个周期。

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  • 原文地址:https://www.cnblogs.com/1114250779boke/p/2788645.html
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