{"problem":{"name":"1-SAT","description":{"content":"Given are $N$ strings $S_1, S_2, \\dots, S_N$. Each of these is a non-empty string consisting of lowercase English letters, with zero or one `!` added at the beginning.   We say a string $T$ to be unsa","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"abc187_c"},"statements":[{"statement_type":"Markdown","content":"Given are $N$ strings $S_1, S_2, \\dots, S_N$. Each of these is a non-empty string consisting of lowercase English letters, with zero or one `!` added at the beginning.  \nWe say a string $T$ to be unsatisfied when it matches one of $S_1, S_2, \\dots, S_N$ regardless of whether we add an `!` at the beginning of $T$.  \nDetermine whether there exists an unsatisfied string. If so, present one such string.\n\n## Constraints\n\n*   $1 \\le N \\le 2 \\times 10^5$\n*   $1 \\le |S_i| \\le 10$\n*   $S_i$ is a non-empty string consisting of lowercase English letters, with zero or one `!` added at the beginning.\n\n## Input\n\nInput is given from Standard Input in the following format:\n\n$N$\n$S_1$\n$\\vdots$\n$S_N$\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"abc187_c","tags":[],"sample_group":[["6\na\n!a\nb\n!c\nd\n!d","a\n\n`a` matches $S_1$ as is, and it matches $S_2$ when we add an `!`, so it is unsatisfied. Besides that, `d` will also be accepted."],["10\nred\nred\nred\n!orange\nyellow\n!blue\ncyan\n!green\nbrown\n!gray","satisfiable"]],"created_at":"2026-03-03 11:01:14"}}