#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;
// const int mod = 998244353; // うくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうくうく

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}

using Real = double;
using Point = complex< Real >;
const Real EPS = 1e-8, PI = acos(-1);

inline bool eq(Real a, Real b) { return fabs(b - a) < EPS; }

Point operator*(const Point &p, const Real &d) {
  return Point(real(p) * d, imag(p) * d);
}

istream &operator>>(istream &is, Point &p) {
  Real a, b;
  is >> a >> b;
  p = Point(a, b);
  return is;
}

ostream &operator<<(ostream &os, Point &p) {
  return os << fixed << setprecision(10) << p.real() << " " << p.imag();
}

// rotate point p counterclockwise by theta rad
Point rotate(Real theta, const Point &p) {
  return Point(cos(theta) * p.real() - sin(theta) * p.imag(), sin(theta) * p.real() + cos(theta) * p.imag());
}

Real radian_to_degree(Real r) {
  return (r * 180.0 / PI);
}

Real degree_to_radian(Real d) {
  return (d * PI / 180.0);
}

// smaller angle of the a-b-c
Real get_angle(const Point &a, const Point &b, const Point &c) {
  const Point v(b - a), w(c - b);
  Real alpha = atan2(v.imag(), v.real()), beta = atan2(w.imag(), w.real());
  if(alpha > beta) swap(alpha, beta);
  Real theta = (beta - alpha);
  return min(theta, 2 * acos(-1) - theta);
}

namespace std {
  bool operator<(const Point &a, const Point &b) {
    return a.real() != b.real() ? a.real() < b.real() : a.imag() < b.imag();
  }
}


struct Line {
  Point a, b;

  Line() = default;

  Line(Point a, Point b) : a(a), b(b) {}

  Line(Real A, Real B, Real C) // Ax + By = C
  {
    if(eq(A, 0)) a = Point(0, C / B), b = Point(1, C / B);
    else if(eq(B, 0)) b = Point(C / A, 0), b = Point(C / A, 1);
    else a = Point(0, C / B), b = Point(C / A, 0);
  }

  friend ostream &operator<<(ostream &os, Line &p) {
    return os << p.a << " to " << p.b;
  }

  friend istream &operator>>(istream &is, Line &a) {
    return is >> a.a >> a.b;
  }
};

struct Segment : Line {
  Segment() = default;

  Segment(Point a, Point b) : Line(a, b) {}
};

struct Circle {
  Point p;
  Real r;

  Circle() = default;

  Circle(Point p, Real r) : p(p), r(r) {}
};

using Points = vector< Point >;
using Polygon = vector< Point >;
using Segments = vector< Segment >;
using Lines = vector< Line >;
using Circles = vector< Circle >;

Real cross(const Point &a, const Point &b) {
  return real(a) * imag(b) - imag(a) * real(b);
}

Real dot(const Point &a, const Point &b) {
  return real(a) * real(b) + imag(a) * imag(b);
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_1_C
int ccw(const Point &a, Point b, Point c) {
  b = b - a, c = c - a;
  if(cross(b, c) > EPS) return +1;  // "COUNTER_CLOCKWISE"
  if(cross(b, c) < -EPS) return -1; // "CLOCKWISE"
  if(dot(b, c) < 0) return +2;      // "ONLINE_BACK" c-a-b
  if(norm(b) < norm(c)) return -2;  // "ONLINE_FRONT" a-b-c
  return 0;                         // "ON_SEGMENT" a-c-b
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_2_A
bool parallel(const Line &a, const Line &b) {
  return eq(cross(a.b - a.a, b.b - b.a), 0.0);
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_2_A
bool orthogonal(const Line &a, const Line &b) {
  return eq(dot(a.a - a.b, b.a - b.b), 0.0);
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_1_A
Point projection(const Line &l, const Point &p) {
  double t = dot(p - l.a, l.a - l.b) / norm(l.a - l.b);
  return l.a + (l.a - l.b) * t;
}

Point projection(const Segment &l, const Point &p) {
  double t = dot(p - l.a, l.a - l.b) / norm(l.a - l.b);
  return l.a + (l.a - l.b) * t;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_1_B
Point reflection(const Line &l, const Point &p) {
  return p + (projection(l, p) - p) * 2.0;
}

bool intersect(const Line &l, const Point &p) {
  return abs(ccw(l.a, l.b, p)) != 1;
}

bool intersect(const Line &l, const Line &m) {
  return abs(cross(l.b - l.a, m.b - m.a)) > EPS || abs(cross(l.b - l.a, m.b - l.a)) < EPS;
}

bool intersect(const Segment &s, const Point &p) {
  return ccw(s.a, s.b, p) == 0;
}

bool intersect(const Line &l, const Segment &s) {
  return cross(l.b - l.a, s.a - l.a) * cross(l.b - l.a, s.b - l.a) < EPS;
}

Real distance(const Line &l, const Point &p);

bool intersect(const Circle &c, const Line &l) {
  return distance(l, c.p) <= c.r + EPS;
}

bool intersect(const Circle &c, const Point &p) {
  return abs(abs(p - c.p) - c.r) < EPS;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_2_B
bool intersect(const Segment &s, const Segment &t) {
  return ccw(s.a, s.b, t.a) * ccw(s.a, s.b, t.b) <= 0 && ccw(t.a, t.b, s.a) * ccw(t.a, t.b, s.b) <= 0;
}

int intersect(const Circle &c, const Segment &l) {
  if(norm(projection(l, c.p) - c.p) - c.r * c.r > EPS) return 0;
  auto d1 = abs(c.p - l.a), d2 = abs(c.p - l.b);
  if(d1 < c.r + EPS && d2 < c.r + EPS) return 0;
  if(d1 < c.r - EPS && d2 > c.r + EPS || d1 > c.r + EPS && d2 < c.r - EPS) return 1;
  const Point h = projection(l, c.p);
  if(dot(l.a - h, l.b - h) < 0) return 2;
  return 0;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_7_A&lang=jp
int intersect(Circle c1, Circle c2) {
  if(c1.r < c2.r) swap(c1, c2);
  Real d = abs(c1.p - c2.p);
  if(c1.r + c2.r < d) return 4;
  if(eq(c1.r + c2.r, d)) return 3;
  if(c1.r - c2.r < d) return 2;
  if(eq(c1.r - c2.r, d)) return 1;
  return 0;
}

Real distance(const Point &a, const Point &b) {
  return abs(a - b);
}

Real distance(const Line &l, const Point &p) {
  return abs(p - projection(l, p));
}

Real distance(const Line &l, const Line &m) {
  return intersect(l, m) ? 0 : distance(l, m.a);
}

Real distance(const Segment &s, const Point &p) {
  Point r = projection(s, p);
  if(intersect(s, r)) return abs(r - p);
  return min(abs(s.a - p), abs(s.b - p));
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_2_D
Real distance(const Segment &a, const Segment &b) {
  if(intersect(a, b)) return 0;
  return min({distance(a, b.a), distance(a, b.b), distance(b, a.a), distance(b, a.b)});
}

Real distance(const Line &l, const Segment &s) {
  if(intersect(l, s)) return 0;
  return min(distance(l, s.a), distance(l, s.b));
}

Point crosspoint(const Line &l, const Line &m) {
  Real A = cross(l.b - l.a, m.b - m.a);
  Real B = cross(l.b - l.a, l.b - m.a);
  if(eq(abs(A), 0.0) && eq(abs(B), 0.0)) return m.a;
  return m.a + (m.b - m.a) * B / A;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_2_C
Point crosspoint(const Segment &l, const Segment &m) {
  return crosspoint(Line(l), Line(m));
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_7_D
pair< Point, Point > crosspoint(const Circle &c, const Line l) {
  Point pr = projection(l, c.p);
  Point e = (l.b - l.a) / abs(l.b - l.a);
  if(eq(distance(l, c.p), c.r)) return {pr, pr};
  double base = sqrt(c.r * c.r - norm(pr - c.p));
  return {pr - e * base, pr + e * base};
}

pair< Point, Point > crosspoint(const Circle &c, const Segment &l) {
  Line aa = Line(l.a, l.b);
  if(intersect(c, l) == 2) return crosspoint(c, aa);
  auto ret = crosspoint(c, aa);
  if(dot(l.a - ret.first, l.b - ret.first) < 0) ret.second = ret.first;
  else ret.first = ret.second;
  return ret;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_7_E
pair< Point, Point > crosspoint(const Circle &c1, const Circle &c2) {
  Real d = abs(c1.p - c2.p);
  Real a = acos((c1.r * c1.r + d * d - c2.r * c2.r) / (2 * c1.r * d));
  Real t = atan2(c2.p.imag() - c1.p.imag(), c2.p.real() - c1.p.real());
  Point p1 = c1.p + Point(cos(t + a) * c1.r, sin(t + a) * c1.r);
  Point p2 = c1.p + Point(cos(t - a) * c1.r, sin(t - a) * c1.r);
  return {p1, p2};
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_7_F
// tangent of circle c through point p
pair< Point, Point > tangent(const Circle &c1, const Point &p2) {
  return crosspoint(c1, Circle(p2, sqrt(norm(c1.p - p2) - c1.r * c1.r)));
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_7_G
// common tangent of circles c1 and c2
Lines tangent(Circle c1, Circle c2) {
  Lines ret;
  if(c1.r < c2.r) swap(c1, c2);
  Real g = norm(c1.p - c2.p);
  if(eq(g, 0)) return ret;
  Point u = (c2.p - c1.p) / sqrt(g);
  Point v = rotate(PI * 0.5, u);
  for(int s : {-1, 1}) {
    Real h = (c1.r + s * c2.r) / sqrt(g);
    if(eq(1 - h * h, 0)) {
      ret.emplace_back(c1.p + u * c1.r, c1.p + (u + v) * c1.r);
    } else if(1 - h * h > 0) {
      Point uu = u * h, vv = v * sqrt(1 - h * h);
      ret.emplace_back(c1.p + (uu + vv) * c1.r, c2.p - (uu + vv) * c2.r * s);
      ret.emplace_back(c1.p + (uu - vv) * c1.r, c2.p - (uu - vv) * c2.r * s);
    }
  }
  return ret;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_3_B
bool is_convex(const Polygon &p) {
  int n = (int) p.size();
  for(int i = 0; i < n; i++) {
    if(ccw(p[(i + n - 1) % n], p[i], p[(i + 1) % n]) == -1) return false;
  }
  return true;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_4_A
Polygon convex_hull(Polygon &p) {
  int n = (int) p.size(), k = 0;
  if(n <= 2) return p;
  sort(p.begin(), p.end());
  vector< Point > ch(2 * n);
  for(int i = 0; i < n; ch[k++] = p[i++]) {
    while(k >= 2 && cross(ch[k - 1] - ch[k - 2], p[i] - ch[k - 1]) < EPS) --k;
  }
  for(int i = n - 2, t = k + 1; i >= 0; ch[k++] = p[i--]) {
    while(k >= t && cross(ch[k - 1] - ch[k - 2], p[i] - ch[k - 1]) < EPS) --k;
  }
  ch.resize(k - 1);
  return ch;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_3_C
enum {
  OUT, ON, IN
};

int contains(const Polygon &Q, const Point &p) {
  bool in = false;
  for(int i = 0; i < Q.size(); i++) {
    Point a = Q[i] - p, b = Q[(i + 1) % Q.size()] - p;
    if(a.imag() > b.imag()) swap(a, b);
    if(a.imag() <= 0 && 0 < b.imag() && cross(a, b) < 0) in = !in;
    if(cross(a, b) == 0 && dot(a, b) <= 0) return ON;
  }
  return in ? IN : OUT;
}


// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1033
// deduplication of line segments
void merge_segments(vector< Segment > &segs) {

  auto merge_if_able = [](Segment &s1, const Segment &s2) {
    if(abs(cross(s1.b - s1.a, s2.b - s2.a)) > EPS) return false;
    if(ccw(s1.a, s2.a, s1.b) == 1 || ccw(s1.a, s2.a, s1.b) == -1) return false;
    if(ccw(s1.a, s1.b, s2.a) == -2 || ccw(s2.a, s2.b, s1.a) == -2) return false;
    s1 = Segment(min(s1.a, s2.a), max(s1.b, s2.b));
    return true;
  };

  for(int i = 0; i < segs.size(); i++) {
    if(segs[i].b < segs[i].a) swap(segs[i].a, segs[i].b);
  }
  for(int i = 0; i < segs.size(); i++) {
    for(int j = i + 1; j < segs.size(); j++) {
      if(merge_if_able(segs[i], segs[j])) {
        segs[j--] = segs.back(), segs.pop_back();
      }
    }
  }
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1033
// construct a graph with the vertex of the intersection of any two line segments
vector< vector< int > > segment_arrangement(vector< Segment > &segs, vector< Point > &ps) {
  vector< vector< int > > g;
  int N = (int) segs.size();
  for(int i = 0; i < N; i++) {
    ps.emplace_back(segs[i].a);
    ps.emplace_back(segs[i].b);
    for(int j = i + 1; j < N; j++) {
      const Point p1 = segs[i].b - segs[i].a;
      const Point p2 = segs[j].b - segs[j].a;
      if(cross(p1, p2) == 0) continue;
      if(intersect(segs[i], segs[j])) {
        ps.emplace_back(crosspoint(segs[i], segs[j]));
      }
    }
  }
  sort(begin(ps), end(ps));
  ps.erase(unique(begin(ps), end(ps)), end(ps));

  int M = (int) ps.size();
  g.resize(M);
  for(int i = 0; i < N; i++) {
    vector< int > vec;
    for(int j = 0; j < M; j++) {
      if(intersect(segs[i], ps[j])) {
        vec.emplace_back(j);
      }
    }
    for(int j = 1; j < vec.size(); j++) {
      g[vec[j - 1]].push_back(vec[j]);
      g[vec[j]].push_back(vec[j - 1]);
    }
  }
  return (g);
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_4_C
// cut with a straight line l and return a convex polygon on the left
Polygon convex_cut(const Polygon &U, Line l) {
  Polygon ret;
  for(int i = 0; i < U.size(); i++) {
    Point now = U[i], nxt = U[(i + 1) % U.size()];
    if(ccw(l.a, l.b, now) != -1) ret.push_back(now);
    if(ccw(l.a, l.b, now) * ccw(l.a, l.b, nxt) < 0) {
      ret.push_back(crosspoint(Line(now, nxt), l));
    }
  }
  return (ret);
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_3_A
Real area(const Polygon &p) {
  Real A = 0;
  for(int i = 0; i < p.size(); ++i) {
    A += cross(p[i], p[(i + 1) % p.size()]);
  }
  return A * 0.5;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_7_H
Real area(const Polygon &p, const Circle &c) {
  if(p.size() < 3) return 0.0;
  function< Real(Circle, Point, Point) > cross_area = [&](const Circle &c, const Point &a, const Point &b) {
    Point va = c.p - a, vb = c.p - b;
    Real f = cross(va, vb), ret = 0.0;
    if(eq(f, 0.0)) return ret;
    if(max(abs(va), abs(vb)) < c.r + EPS) return f;
    if(distance(Segment(a, b), c.p) > c.r - EPS) return c.r * c.r * arg(vb * conj(va));
    auto u = crosspoint(c, Segment(a, b));
    vector< Point > tot{a, u.first, u.second, b};
    for(int i = 0; i + 1 < tot.size(); i++) {
      ret += cross_area(c, tot[i], tot[i + 1]);
    }
    return ret;
  };
  Real A = 0;
  for(int i = 0; i < p.size(); i++) {
    A += cross_area(c, p[i], p[(i + 1) % p.size()]);
  }
  return A;
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_4_B
Real convex_diameter(const Polygon &p) {
  int N = (int) p.size();
  int is = 0, js = 0;
  for(int i = 1; i < N; i++) {
    if(p[i].imag() > p[is].imag()) is = i;
    if(p[i].imag() < p[js].imag()) js = i;
  }
  Real maxdis = norm(p[is] - p[js]);

  int maxi, maxj, i, j;
  i = maxi = is;
  j = maxj = js;
  do {
    if(cross(p[(i + 1) % N] - p[i], p[(j + 1) % N] - p[j]) >= 0) {
      j = (j + 1) % N;
    } else {
      i = (i + 1) % N;
    }
    if(norm(p[i] - p[j]) > maxdis) {
      maxdis = norm(p[i] - p[j]);
      maxi = i;
      maxj = j;
    }
  } while(i != is || j != js);
  return sqrt(maxdis);
}

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_5_A
Real closest_pair(Points ps) {
  if(ps.size() <= 1) throw (0);
  sort(begin(ps), end(ps));

  auto compare_y = [&](const Point &a, const Point &b) {
    return imag(a) < imag(b);
  };
  vector< Point > beet(ps.size());
  const Real INF = 1e18;

  function< Real(int, int) > rec = [&](int left, int right) {
    if(right - left <= 1) return INF;
    int mid = (left + right) >> 1;
    auto x = real(ps[mid]);
    auto ret = min(rec(left, mid), rec(mid, right));
    inplace_merge(begin(ps) + left, begin(ps) + mid, begin(ps) + right, compare_y);
    int ptr = 0;
    for(int i = left; i < right; i++) {
      if(abs(real(ps[i]) - x) >= ret) continue;
      for(int j = 0; j < ptr; j++) {
        auto luz = ps[i] - beet[ptr - j - 1];
        if(imag(luz) >= ret) break;
        ret = min(ret, abs(luz));
      }
      beet[ptr++] = ps[i];
    }
    return ret;
  };
  return rec(0, (int) ps.size());
}


int main() {
  int A, B, H, M;
  cin >> A >> B >> H >> M;
  Point latte(A, 0);
  Point malta(B, 0);
  double angle_latte = H / 12.0 + M / 12.0 / 60.0;
  double angle_malta = M / 60.0;
  angle_latte *= 2 * acos(-1);
  angle_malta *= 2 * acos(-1);
  latte = rotate(angle_latte, latte);
  malta = rotate(angle_malta, malta);
  cout << abs(latte - malta) << "\n";
}


Measured memory_bytes: 4164