{"raw_statement":[{"iden":"problem statement","content":"Three poles stand evenly spaced along a line. Their heights are $a$, $b$ and $c$ meters, from left to right. We will call the arrangement of the poles _beautiful_ if the tops of the poles lie on the same line, that is, $b-a = c-b$.\nDetermine whether the arrangement of the poles is beautiful."},{"iden":"constraints","content":"*   $1 \\leq a,b,c \\leq 100$\n*   $a$, $b$ and $c$ are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$a$ $b$ $c$"},{"iden":"sample input 1","content":"2 4 6"},{"iden":"sample output 1","content":"YES\n\nSince $4-2 = 6-4$, this arrangement of poles is beautiful."},{"iden":"sample input 2","content":"2 5 6"},{"iden":"sample output 2","content":"NO\n\nSince $5-2 \\neq 6-5$, this arrangement of poles is not beautiful."},{"iden":"sample input 3","content":"3 2 1"},{"iden":"sample output 3","content":"YES\n\nSince $1-2 = 2-3$, this arrangement of poles is beautiful."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}