#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <iomanip>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	float speed,sec, ans;
	cin >> speed >> sec;
	cout << fixed << setprecision(0);
	ans = speed * sec - 0.50000;
	cout << ans << endl;
	return 0;
}