function processData(input) {
    //Enter your code here
    var splitInput =input.split(' '),
        m=Number(splitInput[0]),
        n=Number(splitInput[1]);
    
    console.log((m-1)*n)
} 

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});