function main(input){
    var inpArray=input.split(' ');
    var A = parseInt(inpArray[0]);
    var B = parseFloat(inpArray[1]);
    var out = 0;
    var mul = 0;
    mul = A * B;
    out = Math.floor(mul);

    console.log(out);
     
}
     
    main(require("fs").readFileSync("/dev/stdin", "utf8"));