{"problem":{"name":"Fifty-Fifty","description":{"content":"You are given a $4$\\-character string $S$ consisting of uppercase English letters. Determine if $S$ consists of exactly two kinds of characters which both appear twice in $S$.","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"abc132_a"},"statements":[{"statement_type":"Markdown","content":"You are given a $4$\\-character string $S$ consisting of uppercase English letters. Determine if $S$ consists of exactly two kinds of characters which both appear twice in $S$.\n\n## Constraints\n\n*   The length of $S$ is $4$.\n*   $S$ consists of uppercase English letters.\n\n## Input\n\nInput is given from Standard Input in the following format:\n\n$S$\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"abc132_a","tags":[],"sample_group":[["ASSA","Yes\n\n$S$ consists of `A` and `S` which both appear twice in $S$."],["STOP","No"],["FFEE","Yes"],["FREE","No"]],"created_at":"2026-03-03 11:01:14"}}