URAL 1800 Murphy's Law（物理判断题）

1800. Murphy's Law

Time limit: 0.5 second

Memory limit: 64 MB

Anka was awarded a medal and given a buttered toast for displaying heroism in a combat. The toast was so narrow, flat, and thin that it could be regarded as a straight-line segment of length l.
On Commissar Matroskin's advice, Anka turned the toast the buttered side down and, holding it parallel to the ground, brought it to her mouth and was ready to bite, when suddenly…

The toast slipped out of her hands and started falling under gravity. It was rotating at a constant angular velocity about its center of mass in the plane perpendicular to the ground, as shown in the
picture.



Your task is to determine which side of the toast touched the ground first.

Input

The first line contains the length l of the toast in centimeters, the distance h from Anka's mouth to the ground in centimeters, and the angular velocity ω of the toast's rotation
in revolutions per minute (the toast makes one revolution when it turns 360 degrees). 1 ≤ l, h, ω ≤ 1000. These numbers are integers separated with a space. The acceleration of gravity should be taken equal to 9.81 m/s2.

Output

Output “butter” if the toast first touched the ground the buttered side down and “bread” otherwise. It is guaranteed that at the moment the toast touched the ground for the first time it wasn't orthogonal
to it.

Samples

input	output
10 400 15	butter
10 500 15	bread

AC代码：

#include <stdio.h>
#include <math.h>
#define g 9.81
int main(){
double l,h,w,s,q,t;
scanf("%lf%lf%lf",&l,&h,&w);
if(l/2>h)
printf("butter\n");
else{
l/=100;h/=100;w/=60;
h=h-l/2;
t=sqrt(2*h/g);
s=w*t;
q=s-(int)s;
if((q>=0&&q<0.25)||(q>0.75&&q<=1))
printf("butter\n");
else
printf("bread\n");
}
return 0;
}