{"problem":{"name":"String Equivalence","description":{"content":"In this problem, we only consider strings consisting of lowercase English letters. Strings $s$ and $t$ are said to be **isomorphic** when the following conditions are satisfied: *   $|s| = |t|$ holds","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"panasonic2020_d"},"statements":[{"statement_type":"Markdown","content":"In this problem, we only consider strings consisting of lowercase English letters.\nStrings $s$ and $t$ are said to be **isomorphic** when the following conditions are satisfied:\n\n*   $|s| = |t|$ holds.\n*   For every pair $i, j$, one of the following holds:\n    *   $s_i = s_j$ and $t_i = t_j$.\n    *   $s_i \\neq s_j$ and $t_i \\neq t_j$.\n\nFor example, `abcac` and `zyxzx` are isomorphic, while `abcac` and `ppppp` are not.\nA string $s$ is said to be in **normal form** when the following condition is satisfied:\n\n*   For every string $t$ that is isomorphic to $s$, $s \\leq t$ holds. Here $\\leq$ denotes lexicographic comparison.\n\nFor example, `abcac` is in normal form, but `zyxzx` is not since it is isomorphic to `abcac`, which is lexicographically smaller than `zyxzx`.\nYou are given an integer $N$. Print all strings of length $N$ that are in normal form, in lexicographically ascending order.\n\n## Constraints\n\n*   $1 \\leq N \\leq 10$\n*   All values in input are integers.\n\n## Input\n\nInput is given from Standard Input in the following format:\n\n$N$\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"panasonic2020_d","tags":[],"sample_group":[["1","a"],["2","aa\nab"]],"created_at":"2026-03-03 11:01:14"}}