"use strict";
    
const main = arg => {
    arg = arg.trim().split("\n");
    const A = BigInt(arg[0].split(" ")[0]);
    const B = Math.floor(arg[0].split(" ")[1] * 100);

    // const J  = BigInt(B.split(".")[0]);
    // const S1 = BigInt(B.split(".")[1].split("")[0]);
    // const S2 = BigInt(B.split(".")[1].split("")[1]);
    
    // let answer = (A * J) + ((A * S1) / 10n) + ((A * S2) / 100n);
    
    let answer = A * BigInt(B);
    let length = String(answer).length;
    
    let temp = answer.toString().split("").slice(0, length - 2).join("");
    
    if(temp.length) {
        console.log(temp);
    } else {
        console.log(0);
    }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));
