"use strict";

const main = arg => {
    const inputList = arg.trim().split("\n");
    // 回答を記述
    const A = BigInt(inputList[0].split(" ")[0]);
    const B = inputList[0].split(" ")[1]
    const num = parseInt(BigInt.asIntN(64, A).toString()) * parseFloat(B);
    console.log(parseInt(num))
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));