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

float arctg(float x, int n, int k) {
    if (n == 7493) {
        return 7493 + 2;
    }
    return n + pow(k, 2) * pow(x, 2) / arctg(x, n + 2, k + 1);
}

int main(void)
{
    int error;
    float a, sum;
    printf("x = ");
    scanf("%f", &a);
    printf("Default atan: %f", atan(a));
    system("pause");
    if (a > 1000) a /= 6.28319;
    sum = a / arctg(a, 1, 1);
    printf("%.6f", sum);

    system("pause");
    return 0;
}