{"problem":{"name":"180. Boring Strings","description":{"content":"You consider a string of text to be _boring_ if it contains only \"a\" characters and \"b\" characters. For example, \"abbaba\" is boring, while \"abcccbabc\" is not boring. Given a string, figure out whethe","description_type":"Markdown"},"platform":"Codeforces","limit":{"time_limit":1000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"CF10269180"},"statements":[{"statement_type":"Markdown","content":"You consider a string of text to be _boring_ if it contains only \"a\" characters and \"b\" characters. For example, \"abbaba\" is boring, while \"abcccbabc\" is not boring.\n\nGiven a string, figure out whether or not it is a _boring_ string.\n\nThe only line of input contains a single string $s$, not containing spaces.\n\nIf $s$ is _boring_, as described above, output \"YES\" (no quotes). Otherwise, output \"NO\".\n\n## Input\n\nThe only line of input contains a single string $s$, not containing spaces.\n\n## Output\n\nIf $s$ is _boring_, as described above, output \"YES\" (no quotes). Otherwise, output \"NO\".\n\n[samples]","is_translate":false,"language":"English"},{"statement_type":"Markdown","content":"**Definitions**  \nLet $ s \\in \\Sigma^* $ be a string over the alphabet $ \\Sigma $.\n\n**Constraints**  \n$ s $ contains no spaces.\n\n**Objective**  \nDetermine whether $ s \\subseteq \\{a, b\\} $.  \nIf true, output \"YES\"; otherwise, output \"NO\".","is_translate":false,"language":"Formal"}],"meta":{"iden":"CF10269180","tags":[],"sample_group":[],"created_at":"2026-03-03 11:00:39"}}