{"raw_statement":[{"iden":"problem statement","content":"There is a right triangle $ABC$ with $∠ABC=90°$.\nGiven the lengths of the three sides, $|AB|,|BC|$ and $|CA|$, find the area of the right triangle $ABC$.\nIt is guaranteed that the area of the triangle $ABC$ is an integer."},{"iden":"constraints","content":"*   $1 \\leq |AB|,|BC|,|CA| \\leq 100$\n*   All values in input are integers.\n*   The area of the triangle $ABC$ is an integer."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$|AB|$ $|BC|$ $|CA|$"},{"iden":"sample input 1","content":"3 4 5"},{"iden":"sample output 1","content":"6\n\n![image](https://img.atcoder.jp/ghi/44c1d4cbdf4677ce3b08ca70b5ce98ea.png)\nThis triangle has an area of $6$."},{"iden":"sample input 2","content":"5 12 13"},{"iden":"sample output 2","content":"30\n\nThis triangle has an area of $30$."},{"iden":"sample input 3","content":"45 28 53"},{"iden":"sample output 3","content":"630\n\nThis triangle has an area of $630$."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}