#include <stdio.h>
#include <math.h>
int main() {
printf("%f\n", atan(0.5));
printf("%f\n", atan(-0.5));
printf("%f\n", atan(5));
printf("%f\n", atan(-5.0));
printf("%f\n", atan(100.0));
printf("%f\n", atan(-100.0));
return 0;
}