Problem:
Score : 300 points

Problem Statement

Compute A \times B, truncate its fractional part, and print the result as an integer.

Constraints

0 \leq A \leq 10^{15}

0 \leq B < 10

A is an integer.

B is a number with two digits after the decimal point.

Input

Input is given from Standard Input in the following format:

A B

Output

Print the answer as an integer.

Sample Input 1

198 1.10

Sample Output 1

217

We have 198 \times 1.10 = 217.8. After truncating the fractional part, we have the answer: 217.

Sample Input 2

1 0.01

Sample Output 2

0

Sample Input 3

1000000000000000 9.99

Sample Output 3

9990000000000000

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
const int maxn = 500050;
const int inf = 0x3f3f3f3f;
const int mod = 998244353;
const ll linf = 7e18;
ll power(ll x, ll y)
{
    ll ans = 1;
    while (y)
    {
        if (y & 1)
            ans = ans * x % mod;
        x = x * x % mod;
        y >>= 1;
    }
    return ans;
}

ll gcd(ll x, ll y)
{
    if (x % y == 0)
        return y;
    return gcd(y, x % y);
}

bool pa(ll a, ll b)
{
    __int128 x = a, y = b, z = 1e18;
    return x * y <= z;
}

ll a[maxn];

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int i, j, k;
    ll n, ans;
    double m;
    cin >> n >> m;
    ans = m * 100;
    ans = ans * n / 100;
    cout << ans << "\n";
    return 0;
}