{"raw_statement":[{"iden":"problem statement","content":"The window of Takahashi's room has a width of $A$. There are two curtains hung over the window, each of which has a horizontal length of $B$. (Vertically, the curtains are long enough to cover the whole window.)\nWe will close the window so as to minimize the total horizontal length of the uncovered part of the window. Find the total horizontal length of the uncovered parts of the window then."},{"iden":"constraints","content":"*   $1 \\leq A \\leq 100$\n*   $1 \\leq B \\leq 100$\n*   $A$ and $B$ are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$A$ $B$"},{"iden":"sample input 1","content":"12 4"},{"iden":"sample output 1","content":"4\n\nWe have a window with a horizontal length of $12$, and two curtains, each of length $4$, that cover both ends of the window, for example. The uncovered part has a horizontal length of $4$."},{"iden":"sample input 2","content":"20 15"},{"iden":"sample output 2","content":"0\n\nIf the window is completely covered, print $0$."},{"iden":"sample input 3","content":"20 30"},{"iden":"sample output 3","content":"0\n\nEach curtain may be longer than the window."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}