#include <math.h>
#include <stdlib.h>
#include <curses.h>

void func() {
	printf("Input argument X:\n");
	float var = 0;
	if (scanf("%f", &var)) {
		printf("z1: ");
		printf("%.3f", sin(4 * var) * cos(2 * var) / (1 + cos(4 * var)) / (1 + cos(2 * var)));
		printf("\n");
		printf("z2: ");
		printf("%.3f", 1 / tan(3 * M_PI / 2 - var));
		printf("\n");
	} else {
		printf("Wrong input argument X. Press y to continue, other to return back:\n");
		if (121 == getch()) func();
		else return;
	}
}

void list_menu() {
	printf("Choose a menu item:\n");
	printf("1.Calculate\n2.Exit\n");
	int state = 0;
	if (scanf("%d", &state)) {
		switch (state) {
			case 1: {
				func();
				break;
			}
			case 2:
				exit(0);
			default: {
				printf("Please, choose a correct menu item:\n");
				break;
			}
		}
	} else {
		printf("Please, choose a correct menu item:\n");
		list_menu();
	}
}

int main(void) {
	list_menu();
	return 0;
}