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

int main()
{
    int n, x, i;
    
    printf("Unesite n: ");
    scanf("%d", &n);
    printf("Unesite x: ");
    scanf("%d", &x);
    
    float f = 0.0;

    if (n > 0)
    {
        double stepenx = 1.0;   
        double fact = 1.0;      
        double sumaKub = 0.0;

        for (i = 1; i <= n; i++)
        {
            stepenx *= x * x * x;

            if (i == 1)
                fact = 2.0;         
            else
                fact *= (i + 1);     
            sumaKub += i * i * i;

            f += stepenx * (fact / sumaKub);
        }
    }
    else {
        int izraz = 7 * x * x - n;
        if (izraz < 0) izraz = -izraz;

        if (izraz >= 35) {
            f = x + 7 * n;
        }
        else if (izraz > 10 && izraz <= 20) {
            double a = 7 * x;
            double b = 3 * x * x - 5 * x;
            f = a;
            if (b > f) f = b;
            if (20 > f) f = 20;
        }
        else {
            f = sqrt(7 * x * x + n);
        }
    }

    printf("%.2lf\n", f);
    return 0;
}