#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>
#include<bitset>
#include<functional>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000
#define PI 3.14159265358979

using namespace std;
typedef pair<int, int> P;

int main(void) {
	string s;
	int v = 0;
	int t;
	int p;
	int i = 0;
	
	cin >> s >> t;
	while (1) {
		if (s[i] == '.') {
			FOR(u, 0, 3) {
				v += (s[i + 4 - u] - '0')*pow(10, u);
			}
			break;
		}
		i++;
	}
	v = v*t;
	v /= 10000;
	printf("%d\n", v);
	return 0;
}