// 提出時に消す


import java.util.Scanner;

// 提出時にMainに変更する
public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        double a = sc.nextDouble();
        double b = sc.nextDouble();
        double h = sc.nextDouble();
        double m = sc.nextDouble();

        double allmin = h * 60 + m;

        // ans^2 = a^2 + b^2 + 2ab * cos(Ans)
        double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))));

        System.out.println(ans);
        sc.close();
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        double a = sc.nextDouble();
        double b = sc.nextDouble();
        double h = sc.nextDouble();
        double m = sc.nextDouble();

        double allmin = h * 60 + m;

        // ans^2 = a^2 + b^2 + 2ab * cos(Ans)
        double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))));

        System.out.println(ans);
        sc.close();
    }
} Main public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        double a = sc.nextDouble();
        double b = sc.nextDouble();
        double h = sc.nextDouble();
        double m = sc.nextDouble();

        double allmin = h * 60 + m;

        // ans^2 = a^2 + b^2 + 2ab * cos(Ans)
        double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))));

        System.out.println(ans);
        sc.close();
    } main {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        double a = sc.nextDouble();
        double b = sc.nextDouble();
        double h = sc.nextDouble();
        double m = sc.nextDouble();

        double allmin = h * 60 + m;

        // ans^2 = a^2 + b^2 + 2ab * cos(Ans)
        double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))));

        System.out.println(ans);
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double a = sc.nextDouble(); a sc.nextDouble() sc.nextDouble sc double b = sc.nextDouble(); b sc.nextDouble() sc.nextDouble sc double h = sc.nextDouble(); h sc.nextDouble() sc.nextDouble sc double m = sc.nextDouble(); m sc.nextDouble() sc.nextDouble sc double allmin = h * 60 + m; allmin h * 60 + m h * 60 h 60 m double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6))))); ans Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6))))) Math.sqrt Math a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))) a * a + b * b a * a a a b * b b b 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))) b 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))) 2 a b Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))) Math.cos Math Math.toRadians(Math.abs((allmin / 2) - (m * 6))) Math.toRadians Math Math.abs((allmin / 2) - (m * 6)) Math.abs Math (allmin / 2) - (m * 6) (allmin / 2) allmin 2 (m * 6) m 6 System.out.println(ans) System.out.println System.out System System.out ans sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        double a = sc.nextDouble();
        double b = sc.nextDouble();
        double h = sc.nextDouble();
        double m = sc.nextDouble();

        double allmin = h * 60 + m;

        // ans^2 = a^2 + b^2 + 2ab * cos(Ans)
        double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))));

        System.out.println(ans);
        sc.close();
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        double a = sc.nextDouble();
        double b = sc.nextDouble();
        double h = sc.nextDouble();
        double m = sc.nextDouble();

        double allmin = h * 60 + m;

        // ans^2 = a^2 + b^2 + 2ab * cos(Ans)
        double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))));

        System.out.println(ans);
        sc.close();
    }
} Main
// 提出時に消す


import java.util.Scanner;

// 提出時にMainに変更する
public class Main {
    public static void main(String[] args) throws Exception {
        // System.out.println("Hello Java");
        Scanner sc = new Scanner(System.in);
        double a = sc.nextDouble();
        double b = sc.nextDouble();
        double h = sc.nextDouble();
        double m = sc.nextDouble();

        double allmin = h * 60 + m;

        // ans^2 = a^2 + b^2 + 2ab * cos(Ans)
        double ans = Math.sqrt(a * a + b * b - 2 * a * b * Math.cos(Math.toRadians(Math.abs((allmin / 2) - (m * 6)))));

        System.out.println(ans);
        sc.close();
    }
}