{"raw_statement":[{"iden":"problem statement","content":"There are $H$ rows and $W$ columns of white square cells.\nYou will choose $h$ of the rows and $w$ of the columns, and paint all of the cells contained in those rows or columns.\nHow many white cells will remain?\nIt can be proved that this count does not depend on what rows and columns are chosen."},{"iden":"constraints","content":"*   All values in input are integers.\n*   $1 \\leq H, W \\leq 20$\n*   $1 \\leq h \\leq H$\n*   $1 \\leq w \\leq W$"},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$H$ $W$\n$h$ $w$"},{"iden":"sample input 1","content":"3 2\n2 1"},{"iden":"sample output 1","content":"1\n\nThere are $3$ rows and $2$ columns of cells. When two rows and one column are chosen and painted in black, there is always one white cell that remains."},{"iden":"sample input 2","content":"5 5\n2 3"},{"iden":"sample output 2","content":"6"},{"iden":"sample input 3","content":"2 4\n2 4"},{"iden":"sample output 3","content":"0"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}