use std::fmt::Debug;
use std::io::*;

use std::cmp::PartialOrd;
use std::str::*;

use std::string::*;


#[derive(Eq, PartialEq, Clone, Debug)]
pub struct Rev<T>(pub T);

impl<T: PartialOrd> PartialOrd for Rev<T> {
    fn partial_cmp(&self, other: &Rev<T>) -> Option<std::cmp::Ordering> {
        other.0.partial_cmp(&self.0)
    }
}

impl<T: Ord> Ord for Rev<T> {
    fn cmp(&self, other: &Rev<T>) -> std::cmp::Ordering {
        other.0.cmp(&self.0)
    }
}

macro_rules! read {
    (($($t:tt),*)) => {
        ( $(read!($t)),* )
    };
    ([[$t:tt; $len1:expr]; $len2:expr]) => {
        (0..$len2).map(|_| read!([$t; $len1])).collect::<Vec<_>>()
    };

    ([$t:tt; $len:expr]) => {
        (0..$len).map(|_| read!($t)).collect::<Vec<_>>()
    };

    (chars) => {
        read!(String).chars().collect::<Vec<char>>()
    };

    (usize1) => {
        read!(usize) - 1
    };

    ($t:ty) => {{
        let stdin = stdin();
        let stdin = stdin.lock();
        let token: String = stdin
            .bytes()
            .map(|c| c.unwrap() as char)
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect();

        token.parse::<$t>().unwrap()
    }};
}

fn read<T: FromStr>(s: &mut StdinLock) -> T {
    let s: String = s
        .by_ref()
        .bytes()
        .map(|c| c.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();

    return s.parse::<T>().ok().unwrap();
}

macro_rules! input {
    (mut $name:ident: $t:tt, $($r:tt)*) => {
        let mut $name = read!($t);
        input!($($r)*);
    };

    (mut $name:ident: $t:tt) => {
        let mut $name = read!($t);
    };

    ($name:ident: $t:tt, $($r:tt)*) => {
        let $name = read!($t);
        input!($($r)*);
    };

    ($name:ident: $t:tt) => {
        let $name = read!($t);
    };
}

struct Combination {
    MOD: i64,
    fac: Vec<i64>,
    fac_inv: Vec<i64>,
}

impl Combination {
    pub fn new(n: i64) -> Self {
        let MOD: i64 = 1_000_000_007;
        let mut fac: Vec<i64> = vec![0; n as usize + 1];
        let mut fac_inv: Vec<i64> = vec![0; n as usize + 1];

        let get_inverse = |mut n: i64| -> i64 {
            let (mut res, mut p) = (1, MOD - 2);

            while p != 0 {
                if p & 1 == 1 {
                    res = (res * n) % MOD;
                }
                n = (n * n) % MOD;
                p >>= 1;
            }

            return res;
        };

        fac[0] = 1;

        for i in 1..n + 1 {
            fac[i as usize] = (fac[i as usize - 1] * i) % MOD;
        }

        for i in 0..n + 1 {
            fac_inv[i as usize] = get_inverse(fac[i as usize]);
        }

        Combination {
            MOD: MOD,
            fac: fac,
            fac_inv: fac_inv,
        }
    }

    fn nCr(&self, n: i64, r: i64) -> i64 {
        if n < r {
            return 0;
        }

        let a: i64 = self.fac[n as usize];
        let b: i64 = self.fac_inv[(n - r) as usize];
        let c: i64 = self.fac_inv[r as usize];
        let bc: i64 = (b * c) % self.MOD;

        return (a * bc) % self.MOD;
    }

    fn nPr(&self, n: i64, r: i64) -> i64 {
        if n < r {
            return 0;
        }

        let a: i64 = self.fac[n as usize];
        let b: i64 = self.fac_inv[(n - r) as usize];

        return (a * b) % self.MOD;
    }

    fn nHr(&self, n: i64, r: i64) -> i64 {
        if n == 0 && r == 0 {
            return 1;
        }

        return self.nCr(n + r - 1, r);
    }
}

pub trait SliceExt<T>: Iterator + Sized {
    fn vec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

#[derive(Copy, Clone, Eq, PartialEq)]
struct Edge {
    to: usize,
    cost: i64,
}

fn dijkstra(graph: &Vec<Vec<Edge>>, s: &usize) -> Vec<i64> {
    use std::collections::BinaryHeap;
    let mut dist = vec![1e18 as i64; graph.len()];
    let mut heap = BinaryHeap::new();
    dist[*s] = 0;
    heap.push(Rev((0, *s)));
    while let Some(Rev((cost, v))) = heap.pop() {
        if dist[v] < cost {
            continue;
        }

        for e in &graph[v] {
            if dist[e.to] <= dist[v] + e.cost {
                continue;
            }
            dist[e.to] = dist[v] + e.cost;
            heap.push(Rev((dist[e.to], e.to)));
        }
    }
    return dist;
}

struct LCA {
    par: Vec<Vec<Option<usize>>>,
    dist: Vec<i64>,
}

impl LCA {
    pub fn new(graph: &Vec<Vec<usize>>, root: &usize) -> LCA {
        let V = graph.len();
        let mut K = 1;

        while (1 << K) < V {
            K += 1;
        }

        let mut par = vec![vec![None; V]; K];
        let mut dist = vec![-1; V];
        let graph = graph.to_vec();

        fn dfs(
            v: usize,
            p: Option<usize>,
            d: i64,
            graph: &Vec<Vec<usize>>,
            par: &mut Vec<Vec<Option<usize>>>,
            dist: &mut Vec<i64>,
        ) {
            par[0][v] = p;
            dist[v] = d;
            for &to in &graph[v] {
                match p {
                    Some(p) => {
                        if to != p {
                            dfs(to, Some(v), d + 1, graph, par, dist)
                        }
                    }
                    None => dfs(to, Some(v), d + 1, graph, par, dist),
                }
            }
        }

        dfs(*root, None, 0, &graph, &mut par, &mut dist);

        for k in 0..K - 1 {
            for v in 0..V {
                match par[k][v] {
                    Some(x) => par[k + 1][v] = par[k][x],
                    None => (),
                }
            }
        }

        LCA {
            par: par,
            dist: dist,
        }
    }

    pub fn query(&self, u: usize, v: usize) -> usize {
        let mut u = u;
        let mut v = v;
        if self.dist[u] < self.dist[v] {
            return self.query(v, u);
        }

        let K = self.par.len();
        for k in 0..K {
            if ((self.dist[u] - self.dist[v]) >> k & 1) == 1 {
                u = self.par[k][u].unwrap();
            }
        }

        if u == v {
            return u;
        }

        for k in (0..K - 1).rev() {
            if self.par[k][u] != self.par[k][v] {
                u = self.par[k][u].unwrap();
                v = self.par[k][v].unwrap();
            }
        }

        return self.par[0][u].unwrap();
    }
}

struct Doubling {
    N: usize,
    LOG: usize,
    next: Vec<Vec<Option<usize>>>,
}

impl Doubling {
    pub fn new(vec: &Vec<usize>, lim: &usize) -> Doubling {
        let N = vec.len();
        let lim = *lim;
        let mut LOG = 1;
        while (1 << LOG) < 2 * lim {
            LOG += 1;
        }

        let mut next = vec![vec![None; N]; LOG];

        for i in 0..N {
            next[0][i] = Some(vec[i]);
        }

        for k in 0..LOG - 1 {
            for i in 0..N {
                match next[k][i] {
                    Some(x) => next[k + 1][i] = next[k][x],
                    None => (),
                }
            }
        }

        Doubling {
            N: N,
            LOG: LOG,
            next: next,
        }
    }

    pub fn query(&self, i: usize, n: usize) -> usize {
        let mut i = i;
        for k in (0..self.LOG).rev() {
            if (n >> k) & 1 == 1 {
                i = self.next[k][i].unwrap();
            }
        }
        return i;
    }
}

macro_rules! min {
    ($a:expr $(,)*) => {{
        $a
    }};
    ($a:expr, $b:expr $(,)*) => {{
        std::cmp::min($a, $b)
    }};
    ($a:expr, $($rest:expr),+ $(,)*) => {{
        std::cmp::min($a, min!($($rest),+))
    }};
}

macro_rules! chmin {
    ($base:expr, $($cmps:expr),+ $(,)*) => {{
        let cmp_min = min!($($cmps),+);
        if $base > cmp_min {
            $base = cmp_min;
            true
        } else {
            false
        }
    }};
}

macro_rules! max {
    ($a:expr $(,)*) => {{
        $a
    }};
    ($a:expr, $b:expr $(,)*) => {{
        std::cmp::max($a, $b)
    }};
    ($a:expr, $($rest:expr),+ $(,)*) => {{
        std::cmp::max($a, max!($($rest),+))
    }};
}

macro_rules! chmax {
    ($base:expr, $($cmps:expr),+ $(,)*) => {{
        let cmp_max = max!($($cmps),+);
        if $base < cmp_max {
            $base = cmp_max;
            true
        } else {
            false
        }
    }};
}

trait Semigroup {
    fn op(&self, other: &Self) -> Self;
}

trait Monoid: Semigroup {
    fn identity() -> Self;
}

impl<T: Semigroup + Clone> Semigroup for Option<T> {
    fn op(&self, other: &Self) -> Self {
        match self {
            Some(ref a) => match other {
                Some(ref b) => Some(a.op(b)),
                None => self.clone(),
            },
            None => other.clone(),
        }
    }
}



fn main() {
    input!(a: i64, b: String);
    let b = b.chars().collect::<Vec<char>>();
    let b100 = (b[0] as i64 - '0' as i64) * 100 + (b[2] as i64 - '0' as i64) * 10 + (b[3] as i64 - '0' as i64);
    println!("{}", a * b100 / 100);
}



Measured memory_bytes: 2116