// >>> TEMPLATES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using i32 = int32_t;
using i64 = int64_t;
#define int ll
#define double ld
#define rep(i,n) for (int i = 0; i < (int)(n); i++)
#define rep1(i,n) for (int i = 1; i <= (int)(n); i++)
#define repR(i,n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep1R(i,n) for (int i = (int)(n); i >= 1; i--)
#define loop(i,a,B) for (int i = a; i B; i++)
#define loopR(i,a,B) for (int i = a; i B; i--)
#define all(x) (x).begin(), (x).end()
#define allR(x) (x).rbegin(), (x).rend()
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fst first
#define snd second
auto constexpr INF32 = numeric_limits<int32_t>::max()/2-1;
auto constexpr INF64 = numeric_limits<int64_t>::max()/2-1;
auto constexpr INF   = numeric_limits<int>::max()/2-1;
#ifdef LOCAL
#include "debug.hpp"
#define dump(...) cerr << "[" << setw(3) << __LINE__ << ":" << __FUNCTION__ << "] ", dump_impl(#__VA_ARGS__, __VA_ARGS__)
#define say(x) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] " << x << endl
#define debug if (1)
#else
#define dump(...) (void)(0)
#define say(x) (void)(0)
#define debug if (0)
#endif
template <class T> using pque_max = priority_queue<T>;
template <class T> using pque_min = priority_queue<T, vector<T>, greater<T> >;
template <class T, class = typename T::iterator, class = typename enable_if<!is_same<T, string>::value>::type>
ostream& operator<<(ostream& os, T const& v) { bool f = true; for (auto const& x : v) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, class = typename T::iterator, class = typename enable_if<!is_same<T, string>::value>::type>
istream& operator>>(istream& is, T &v) { for (auto& x : v) is >> x; return is; }
template <class T, class S> istream& operator>>(istream& is, pair<T,S>& p) { return is >> p.first >> p.second; }
struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;
template <class F> struct FixPoint : private F {
    constexpr FixPoint(F&& f) : F(forward<F>(f)) {}
    template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }
};
struct MakeFixPoint {
    template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); }
};
#define MFP MakeFixPoint()|
#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)
template <class T, size_t d> struct vec_impl {
    using type = vector<typename vec_impl<T,d-1>::type>;
    template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T,d-1>::make_v(forward<U>(x)...)); }
};
template <class T> struct vec_impl<T,0> { using type = T; static type make_v(T const& x = {}) { return x; } };
template <class T, size_t d = 1> using vec = typename vec_impl<T,d>::type;
template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T,d>::make_v(forward<Args>(args)...); }
template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > y) { x = y; return true; } return false; }
template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < y) { x = y; return true; } return false; }
template <class It> constexpr auto sumof(It b, It e) { return accumulate(b,e,typename iterator_traits<It>::value_type{}); }
template <class T> int sz(T const& x) { return x.size(); }
template <class C, class T> int lbd(C const& v, T const& x) {
    return lower_bound(v.begin(), v.end(), x)-v.begin();
}
template <class C, class T> int ubd(C const& v, T const& x) {
    return upper_bound(v.begin(), v.end(), x)-v.begin();
}
template <class C, class F> int ppt(C const& v, F f) {
    return partition_point(v.begin(), v.end(), f)-v.begin();
}
// <<<
// >>> Point
template <class T>
struct Point {
    T x,y;
    constexpr Point(T x = 0, T y = 0) : x(x), y(y) {}
    constexpr pair<T,T> to_pair() const { return {x,y}; }
    constexpr Point inv() const { return {x/norm(),-y/norm()}; }
    constexpr Point conj() const { return {x,-y}; }
    constexpr T norm() const { return x*x + y*y; }
    constexpr Point rot90(int n = 1) const {
        n %= 4; if (n < 0) n += 4;
        if (n == 1) return *this * Point(0,1);
        if (n == 2) return *this * (-1);
        if (n == 3) return *this * Point(0,-1);
        return *this;
    }
    constexpr Point operator+() const { return *this; }
    constexpr Point operator-() const { return {-x,-y}; }
    constexpr Point operator+(Point const& p) const { return {x+p.x, y+p.y}; }
    constexpr Point operator-(Point const& p) const { return {x-p.x, y-p.y}; }
    constexpr Point operator*(Point const& p) const { return {x*p.x-y*p.y, x*p.y+y*p.x}; }
    constexpr Point operator/(Point const& p) const { return *this * p.inv(); }
    constexpr friend Point operator*(T const& a, Point const& p) { return Point(a)*p; }
    constexpr friend Point operator/(T const& a, Point const& p) { return Point(a)/p; }
    constexpr T dot(Point const& q) const { return x*q.x + y*q.y; }
    constexpr T cross(Point const& q) const { return x*q.y - y*q.x; }

    constexpr friend Point conj(Point const& p) { return p.conj(); }
    constexpr friend T norm(Point const& p) { return p.x*p.x + p.y*p.y; }
    constexpr friend T dot(Point const& p, Point const& q) { return p.dot(q); }
    constexpr friend T cross(Point const& p, Point const& q) { return p.cross(q); }
#ifdef LOCAL
    friend string to_s(Point const& p) { return to_s(p.to_pair()); }
#endif
    friend istream& operator>>(istream& is, Point& p) { return is >> p.x >> p.y; }
};
// <<<

using Real = double;
using P = Point<Real>;
constexpr Real eps = 1e-10;
constexpr Real pi = acos(-1.0L);
constexpr Real to_rad(int deg) { return Real(deg) * pi / 180; }
constexpr Real to_deg(Real rad) { return rad * 180 / pi; }

constexpr Real abs(Point<Real> const& p) { return sqrt(p.norm()); }
constexpr Point<Real> normalize(Point<Real> const& p) { return p/abs(p); }

template <class T> constexpr T sq(T const& x) { return x*x; }

int32_t main() {
    double A,B,H,M; cin >> A >> B >> H >> M;

    double theta_H = 2*pi*(H*60+M)/60/12;
    double theta_M = 2*pi*M/60;

    P h(A*cos(theta_H),A*sin(theta_H));
    P m(B*cos(theta_M),B*sin(theta_M));
    cout << abs(h-m) << endl;
}


Measured memory_bytes: 4188