{"raw_statement":[{"iden":"problem statement","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."},{"iden":"constraints","content":"*   $1 \\le N \\le 2 \\times 10^5$\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."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$S_1$\n$\\vdots$\n$S_N$"},{"iden":"sample input 1","content":"6\na\n!a\nb\n!c\nd\n!d"},{"iden":"sample output 1","content":"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."},{"iden":"sample input 2","content":"10\nred\nred\nred\n!orange\nyellow\n!blue\ncyan\n!green\nbrown\n!gray"},{"iden":"sample output 2","content":"satisfiable"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}