{"raw_statement":[{"iden":"problem statement","content":"How many ways are there to choose two distinct positive integers totaling $N$, disregarding the order?"},{"iden":"constraints","content":"*   $1 \\leq N \\leq 10^6$\n*   $N$ is an integer."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$"},{"iden":"sample input 1","content":"4"},{"iden":"sample output 1","content":"1\n\nThere is only one way to choose two distinct integers totaling $4$: to choose $1$ and $3$. (Choosing $3$ and $1$ is not considered different from this.)"},{"iden":"sample input 2","content":"999999"},{"iden":"sample output 2","content":"499999"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}