{"raw_statement":[{"iden":"problem statement","content":"There are $N$ apple trees in a row. People say that one of them will bear golden apples.\nWe want to deploy some number of inspectors so that each of these trees will be inspected.\nEach inspector will be deployed under one of the trees. For convenience, we will assign numbers from $1$ through $N$ to the trees. An inspector deployed under the $i$\\-th tree $(1 \\leq i \\leq N)$ will inspect the trees with numbers between $i-D$ and $i+D$ (inclusive).\nFind the minimum number of inspectors that we need to deploy to achieve the objective."},{"iden":"constraints","content":"*   All values in input are integers.\n*   $1 \\leq N \\leq 20$\n*   $1 \\leq D \\leq 20$"},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$ $D$"},{"iden":"sample input 1","content":"6 2"},{"iden":"sample output 1","content":"2\n\nWe can achieve the objective by, for example, placing an inspector under Tree $3$ and Tree $4$."},{"iden":"sample input 2","content":"14 3"},{"iden":"sample output 2","content":"2"},{"iden":"sample input 3","content":"20 4"},{"iden":"sample output 3","content":"3"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}