#include<iostream>
using namespace std;
int main(){
    double a, b;
    cin>>a>>b;
    int c = a*b/10;
    if(c%10 >= 5){
        c = c-c%10+10;
    }else{
        c = c-c%10;
    }
    cout<<c;
    return 0;
}

#include <bits/stdc++.h> using namespace std;

int main() { int a; double b; int c; cin >> a >> b; b = b / 10; c = a * b; c = c + 5; c = c / 10; c = c * 10; cout << c; return 0; }

#include <bits/stdc++.h>
using namespace std;
int n;
double k;

int main() {
	cin >> n >> k;


	k = (n * (k / 10));
	k /= 10;
	k = round(k) * 10;
	cout << k;



	return 0;
}