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: Accepted)

#include <bits/stdc++.h>
using namespace std;

// 型名の省略
typedef unsigned int uint;
typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> P;
typedef pair<lint, lint> Plint;
 
const int MOD = 1e9+7;
const int INF = 1<<18;
const lint INFLINT = 1LL<<60;
const double PI=acos(-1.0);
 
// cinとcoutの高速化
#define endl "\n"
struct cinacc{cinacc(){cin.tie(0);ios::sync_with_stdio(false);}}cinaccc;
struct coutacc{coutacc(){cout.setf(ios::fixed);cout.precision(12);}}coutaccc;
 
// 繰り返し
#define rep(i,n) for(lint i=0;i<(lint)(n);i++)
#define reps(i,n) for(lint i=0;i<=(lint)(n);i++)
#define rrep(i,n) for(lint i=(lint)(n)-1;i>0;i--)
#define rreps(i,n) for(lint i=(lint)(n)-1;i>=0;i--)

#define pb push_back

#define ALL(s) (s.begin(), s.end())
#define SZ(s) (s.size())

template<class T>bool chmax(T&a,const T&b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T&a,const T&b){if(b<a){a=b;return true;}return false;}

// Union-Find-Tree
class UnionFind {
	vector<int> par;
	UnionFind(int n):par(n){rep(i,n)par[i]=i;}
	int root(int x){if(par[x]==x)return x;return par[x]=root(par[x]);}
	void unite(int x,int y){int rx=root(x);int ry=root(y);if(rx==ry)return;par[rx]=ry;}
	bool same(int x,int y){return root(x)==root(y);}
};

// Final Weapon!
// #define int lint

int main() {
    int a, b, x, y, n, m, h;
    string s;
    
    cin >> a >> b >> h >> m;
    
    double C = abs((h * 30.0 + m * 0.5) - m * 6.0);
    double c = sqrt(a * a + b * b - 2 * a * b * cos(C * PI / 180));
    cout << c;
    
    return 0;
}