Problem:
Score: 300 points

Problem Statement

Consider an analog clock whose hour and minute hands are A and B centimeters long, respectively.

An endpoint of the hour hand and an endpoint of the minute hand are fixed at the same point, around which each hand rotates clockwise at constant angular velocity. It takes the hour and minute hands 12 hours and 1 hour to make one full rotation, respectively.

At 0 o'clock, the two hands overlap each other. H hours and M minutes later, what is the distance in centimeters between the unfixed endpoints of the hands?

Constraints

All values in input are integers.

1 \leq A, B \leq 1000

0 \leq H \leq 11

0 \leq M \leq 59

Input

Input is given from Standard Input in the following format:

A B H M

Output

Print the answer without units. Your output will be accepted when its absolute or relative error from the correct value is at most 10^{-9}.

Sample Input 1

3 4 9 0

Sample Output 1

5.00000000000000000000

The two hands will be in the positions shown in the figure below, so the answer is 5 centimeters.

Sample Input 2

3 4 10 40

Sample Output 2

4.56425719433005567605

The two hands will be in the positions shown in the figure below. Note that each hand always rotates at constant angular velocity.

Solution in C (GCC 9.2.1) (judge verdict: Wrong Answer)

/*  ex4_2
    Rikuta  */

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

#define PI 3.141592653589793

int main(void){

    double hour_hand_length,min_hand_length,num_hour,num_min;

    //入力受け取り
    scanf("%d %d %d %d",&hour_hand_length,&min_hand_length,&num_hour,&num_min);

    //何時何分を分になおす
    double sum_mins=60*num_hour+num_min;

    //時針と分針の0:00からの弧度
    double hour_hand_radian=(double)sum_mins/360*PI;
    double min_hand_radian=(double)num_min/30*PI;

    //時針と分針の間の弧度
    double dif_radian=hour_hand_radian-min_hand_radian;

    //余弦定理をつかった答えの計算
    double ans=sqrt(pow((double)hour_hand_length,2)+pow((double)min_hand_length,2)-2*hour_hand_length*min_hand_length*cos(dif_radian));

    //答えの出力
    printf("%lf\n",ans);

    return 0;
}