#include <stdio.h>
#include <math.h>
int main() {
const double PI = 3.141592653589793;
printf("%f\n", cos(3));
printf("%f\n", cos(-3));
printf("%f\n", cos(0));
printf("%f\n", cos(PI));
printf("%f\n", cos(PI / 2.0));
return 0;
}