import java.util.Scanner;
import java.util.*;
public class Main{

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
      //数字の数を入力
		int a = sc.nextInt();
		int b = sc.nextInt();
		int h = sc.nextInt();
		int m = sc.nextInt();
      //短針が進む角度
      double tanshin = 0.5 *m + 30*h;
      //長針
      double tyoshin = 6 * m;
      //なす角度
      double kakudo = tanshin - tyoshin;

        if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	}
        if(kakudo < 0){
        	kakudo *= -1;
        }
        
      	double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo));
      	double result = Math.sqrt(result2);
      	System.out.println(result);
      
      }             
      
	}
 import java.util.Scanner; Scanner java.util import java.util.*; util.* java public class Main{

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
      //数字の数を入力
		int a = sc.nextInt();
		int b = sc.nextInt();
		int h = sc.nextInt();
		int m = sc.nextInt();
      //短針が進む角度
      double tanshin = 0.5 *m + 30*h;
      //長針
      double tyoshin = 6 * m;
      //なす角度
      double kakudo = tanshin - tyoshin;

        if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	}
        if(kakudo < 0){
        	kakudo *= -1;
        }
        
      	double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo));
      	double result = Math.sqrt(result2);
      	System.out.println(result);
      
      }             
      
	} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
      //数字の数を入力
		int a = sc.nextInt();
		int b = sc.nextInt();
		int h = sc.nextInt();
		int m = sc.nextInt();
      //短針が進む角度
      double tanshin = 0.5 *m + 30*h;
      //長針
      double tyoshin = 6 * m;
      //なす角度
      double kakudo = tanshin - tyoshin;

        if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	}
        if(kakudo < 0){
        	kakudo *= -1;
        }
        
      	double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo));
      	double result = Math.sqrt(result2);
      	System.out.println(result);
      
      } main {
		Scanner sc = new Scanner(System.in);
      //数字の数を入力
		int a = sc.nextInt();
		int b = sc.nextInt();
		int h = sc.nextInt();
		int m = sc.nextInt();
      //短針が進む角度
      double tanshin = 0.5 *m + 30*h;
      //長針
      double tyoshin = 6 * m;
      //なす角度
      double kakudo = tanshin - tyoshin;

        if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	}
        if(kakudo < 0){
        	kakudo *= -1;
        }
        
      	double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo));
      	double result = Math.sqrt(result2);
      	System.out.println(result);
      
      } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int h = sc.nextInt(); h sc.nextInt() sc.nextInt sc int m = sc.nextInt(); m sc.nextInt() sc.nextInt sc double tanshin = 0.5 *m + 30*h; tanshin 0.5 *m + 30*h 0.5 *m 0.5 m 30*h 30 h double tyoshin = 6 * m; tyoshin 6 * m 6 m double kakudo = tanshin - tyoshin; kakudo tanshin - tyoshin tanshin tyoshin if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	} kakudo > 180 kakudo 180 {
        	kakudo = 360 - kakudo;
      	} kakudo = 360 - kakudo kakudo 360 - kakudo 360 kakudo if(kakudo < 0){
        	kakudo *= -1;
        } kakudo < 0 kakudo 0 {
        	kakudo *= -1;
        } kakudo *= -1 kakudo -1 1 double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo)); result2 a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo)) a*a + b*b a*a a a b*b b b 2*a*b* Math.cos(Math.toRadians(kakudo)) b 2*a*b* Math.cos(Math.toRadians(kakudo)) 2 a b Math.cos(Math.toRadians(kakudo)) Math.cos Math Math.toRadians(kakudo) Math.toRadians Math kakudo double result = Math.sqrt(result2); result Math.sqrt(result2) Math.sqrt Math result2 System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main{

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
      //数字の数を入力
		int a = sc.nextInt();
		int b = sc.nextInt();
		int h = sc.nextInt();
		int m = sc.nextInt();
      //短針が進む角度
      double tanshin = 0.5 *m + 30*h;
      //長針
      double tyoshin = 6 * m;
      //なす角度
      double kakudo = tanshin - tyoshin;

        if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	}
        if(kakudo < 0){
        	kakudo *= -1;
        }
        
      	double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo));
      	double result = Math.sqrt(result2);
      	System.out.println(result);
      
      }             
      
	} public class Main{

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
      //数字の数を入力
		int a = sc.nextInt();
		int b = sc.nextInt();
		int h = sc.nextInt();
		int m = sc.nextInt();
      //短針が進む角度
      double tanshin = 0.5 *m + 30*h;
      //長針
      double tyoshin = 6 * m;
      //なす角度
      double kakudo = tanshin - tyoshin;

        if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	}
        if(kakudo < 0){
        	kakudo *= -1;
        }
        
      	double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo));
      	double result = Math.sqrt(result2);
      	System.out.println(result);
      
      }             
      
	} Main
import java.util.Scanner;
import java.util.*;
public class Main{

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
      //数字の数を入力
		int a = sc.nextInt();
		int b = sc.nextInt();
		int h = sc.nextInt();
		int m = sc.nextInt();
      //短針が進む角度
      double tanshin = 0.5 *m + 30*h;
      //長針
      double tyoshin = 6 * m;
      //なす角度
      double kakudo = tanshin - tyoshin;

        if(kakudo > 180){
        	kakudo = 360 - kakudo;
      	}
        if(kakudo < 0){
        	kakudo *= -1;
        }
        
      	double result2 = a*a + b*b - 2*a*b* Math.cos(Math.toRadians(kakudo));
      	double result = Math.sqrt(result2);
      	System.out.println(result);
      
      }             
      
	}

