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地址：http://codeforces.com/contest/768/problem/D 题目： D. Jon and Orbs time limit per test 2 seconds memory limit per test 256 megabytes input standard in 阅读全文
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地址：http://codeforces.com/contest/768/problem/C 题目： C. Jon Snow and his Favourite Number time limit per test 4 seconds memory limit per test 256 megaby 阅读全文
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地址：http://codeforces.com/contest/768/problem/B 题目： B. Code For 1 time limit per test 2 seconds memory limit per test 256 megabytes input standard inpu 阅读全文
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地址：http://codeforces.com/problemset/problem/768/A 题目： A. Oath of the Night's Watch time limit per test 2 seconds memory limit per test 256 megabytes i 阅读全文