fourth

#include <iostream>
#define _USE_MATH_DEFINES
#include <math.h>
using namespace std;

int main() {

	double x, a;
	cout << "Enter \"x\" value\n";
	cin >> x;
	while (getchar() != '\n')
		;
	cout << "Enter \"a\" value or press \"Enter\" to make it 1\n";
	char c;
	c = cin.peek();
	if (c == '\n')
		a = 1;
	else
		cin >> a;
	double M;
	if (x == 0 || (x < -3) || (log(a + x) + pow(M_E, a) == 0))){
		cout << "undefined";
	return 0;
	}
	M = (2 * x * x + sqrt(x + 3)) / ((log(a + x) + pow(M_E, a)) * atan(x));
	cout << M;
	return 0;
}