#include <stdio.h>
#include <math.h>

int main() {
    double a, b, x, f1, f2, f3;
    int n;
    printf("vvedite a,b,x\n");
    scanf("%lf %lf %lf", &a, &b, &x);
    printf("vvedite n\n");
    scanf("%i", &n);
    switch (n) {

        case 1:
            if (x != 0) {
                f1 = (a * b / tan(x));
                printf("%f", f1);
            } else {
                printf("net reshenia");
            }
            break;

        case 2:
            if (x != 0 && a != 0 && b != 0) {
                f2 = (a * b / tan(x)) / (tan(x) + fabs(a * b));
                printf("%f", f2);
            } else {
                printf("net reshenia");
            }
            break;

        case 3:
            if (x != 0 && a > 0 && b != 0) {
                f3 = (a * b / tan(x)) / (log(a) + fabs(b - x));
                printf("%f", f3);
            } else {
                printf("net reshenia ");
            }
            break;
        default:
            printf("nepravilniy n");
    }
}