#include <stdio.h>
#include <math.h>
int main() {
printf("%f\n", log2(64.0));
printf("%f\n", log2(10.0));
printf("%f\n", log2(3.1623));
printf("%f\n", log2(1.0));
printf("%f\n", log2(0.0));
printf("%f\n", log2(-1.0));
return 0;
}