"use strict";
function main(input) {
    const line = input.split("\n");
    let lineOne = line[0].split(" ");
    const a = parseInt(lineOne[0]);
    const b = parseFloat(lineOne[1]);
    let c = (a*b);
    c = c.toString();
    c = c.split(".");
    console.log(c[0]);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));
//main(require('fs').readFileSync('input.txt', 'utf8'));