// C++ program to multiply two numbers 
// represented as strings. 
#include <bits/stdc++.h> 
using namespace std; 

// Multiplies str1 and str2, and prints result. 
string multiply(string num1, string num2) 
{ 
	int n1 = num1.size(); 
	int n2 = num2.size(); 
	if (n1 == 0 || n2 == 0) 
		return "0"; 

	// will keep the result number in vector 
	// in reverse order 
	vector<int> result(n1 + n2, 0); 

	// Below two indexes are used to find positions 
	// in result. 
	int i_n1 = 0; 
	int i_n2 = 0; 

	// Go from right to left in num1 
	for (int i = n1 - 1; i >= 0; i--) { 
		int carry = 0; 
		int n1 = num1[i] - '0'; 

		// To shift position to left after every 
		// multiplication of a digit in num2 
		i_n2 = 0; 

		// Go from right to left in num2 
		for (int j = n2 - 1; j >= 0; j--) { 
			// Take current digit of second number 
			int n2 = num2[j] - '0'; 

			// Multiply with current digit of first number 
			// and add result to previously stored result 
			// at current position. 
			int sum = n1 * n2 + result[i_n1 + i_n2] + carry; 

			// Carry for next iteration 
			carry = sum / 10; 

			// Store result 
			result[i_n1 + i_n2] = sum % 10; 

			i_n2++; 
		} 

		// store carry in next cell 
		if (carry > 0) 
			result[i_n1 + i_n2] += carry; 

		// To shift position to left after every 
		// multiplication of a digit in num1. 
		i_n1++; 
	} 

	// ignore '0's from the right 
	int i = result.size() - 1; 
	while (i >= 0 && result[i] == 0) 
		i--; 

	// If all were '0's - means either both or 
	// one of num1 or num2 were '0' 
	if (i == -1) 
		return "0"; 

	// generate the result string 
	string s = ""; 
	while (i >= 0) 
		s += std::to_string(result[i--]); 

	return s; 
} 

// Driver code 
int main() 
{ 
	string str1 = "454545454545454545"; 

	cout << multiply(str1, str1); 

	return 0; 
}