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 JavaScript (Node.js 12.16.1) (judge verdict: Runtime Error)

function Scanner(input) {
	var self = this;
	self.itemNo = 0;
	self.orgStr = input;
	self.splitedStrs = (function(target) {
		var result = [];
		var target = target.replace(/[\n \t]+/g, " ");
		var strs = target.split(" ");
		for (var i = 0, len = strs.length; i < len; i++) {
			result.push(strs[i]);
		}
		return result;
	}(input));

	self.next = function() {
		var result = self.splitedStrs[self.itemNo];
		self.itemNo++;
		return (result != null) ? result : null;
	}

	self.nextInt = function() {
		var result = self.splitedStrs[self.itemNo];
		self.itemNo++;
		return (result != null) ? parseInt(result) : null;
	}

	self.nextBigDecimal = function() {
		var result = self.splitedStrs[self.itemNo];
		self.itemNo++;
		return (result != null) ? parseFloat(result) : null;
	}
	
	self.nextByte = function() {
		var result = self.splitedStrs[self.itemNo];
		self.itemNo++;
		return (result != null) ? new Int8Array(result) : null;
	}

}

function Main(sc) {
	
	var A = BigInt(sc.next());
	var B = sc.nextBigDecimal();
	
	var B2 = BigInt(parseInt(Math.floor(B * 100));
	
	var ans = A * B2;
	if (ans >= BigInt(100)) {
		ans = ans.toString();
		ans = ans.substring(0, ans.length - 2);
	} else {
		ans = 0;
	}
	
	console.log(ans);
}
Main(new Scanner(require("fs").readFileSync("/dev/stdin", "utf8")));
// Main(new Scanner("10 1 2 5 3 4 6 7 3 2 4 1 2 2 3 3 4 4 5 3 6 6 7 1 8 8 9 9 10"));

// var str1 = sc.next(); // Stringで取得
// var int1 = sc.nextInt(); // intで取得
// var bd1 = sc.nextBigDecimal(); // BigDecimalで取得
// var byte1 = sc.nextByte(); // byteで取得
// for (var i = 0; i < 1000000000; i++) var toDelay = "aaa"; // 1000msくらいの遅延
// console.log(wrtnNos); return;