#include <bits/stdc++.h>
const int MOD = 1000000007;
const int INF = 1000000000;
using namespace std;
const double eps = 1e-10;
const int inf = 1e9;
static const int COUNTER_CLOCKWISE = 1;
static const int CLOCKWISE = -1;
static const int ONLINE_BACK = 2;
static const int ONLINE_FRONT = -2;
static const int ON_SEGMENT = 0;
class Point {
 public:
  double x, y;
  Point(double x, double y) : x(x), y(y) {}
  Point operator+(const Point &p) { return Point(x + p.x, y + p.y); }
  Point operator-(const Point &p) { return Point(x - p.x, y - p.y); }
  Point operator*(double k) { return Point(x * k, y * k); }
  Point operator/(double k) { return Point(x / k, y / k); }
  bool operator<(const Point &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const Point &p) const {
    return fabs(x - p.x) < eps && fabs(y - p.y) < eps;
  }
  double abs() { return sqrt(norm()); }
  double norm() { return x * x + y * y; }
};
double dot(Point a, Point b) { return a.x * b.x + a.y * b.y; }
double cross(Point a, Point b) { return a.x * b.y - a.y * b.x; }
double norm(Point a) { return a.x * a.x + a.y * a.y; }
double abs(Point a) { return sqrt(norm(a)); }
struct Segment {
  Point p1, p2;
  Segment(Point p1, Point p2) : p1(p1), p2(p2) {}
};
class Circle {
 public:
  Point c;
  double r;
  Circle(Point c, double r) : c(c), r(r) {}
};
bool isorthogonal(Point a, Point b) { return fabs(dot(a, b) - 0.0) < eps; }
bool isparallel(Point a, Point b) { return fabs(cross(a, b) - 0.0) < eps; }
Point project(Segment s, Point p) {
  Point base = s.p2 - s.p1;
  double r = dot(p - s.p1, base) / norm(base);
  return s.p1 + base * r;
}
Point reflect(Segment s, Point p) { return p + (project(s, p) - p) * 2.0; }
double getdistance(Point a, Point b) { return abs(a - b); }
double getdistanceLP(Segment l, Point p) {
  return abs(cross(l.p2 - l.p1, p - l.p1) / abs(l.p2 - l.p1));
}
double getdistanceSP(Segment s, Point p) {
  if (dot(s.p2 - s.p1, p - s.p1) < 0.0) return abs(p - s.p1);
  if (dot(s.p1 - s.p2, p - s.p2) < 0.0) return abs(p - s.p2);
  return getdistanceLP(s, p);
}
int ccw(Point p0, Point p1, Point p2) {
  Point a = p1 - p0;
  Point b = p2 - p0;
  if (cross(a, b) > eps) return COUNTER_CLOCKWISE;
  if (cross(a, b) < -eps) return CLOCKWISE;
  if (dot(a, b) < -eps) return ONLINE_BACK;
  if (a.norm() < b.norm()) return ONLINE_FRONT;
  return ON_SEGMENT;
}
bool intersect(Point p1, Point p2, Point p3, Point p4) {
  return (ccw(p1, p2, p3) * ccw(p1, p2, p4) <= 0 &&
          ccw(p3, p4, p1) * ccw(p3, p4, p2) <= 0);
}
bool intersect(Segment s1, Segment s2) {
  return intersect(s1.p1, s1.p2, s2.p1, s2.p2);
}
Point getcrosspoint(Segment s1, Segment s2) {
  Point base = s2.p2 - s2.p1;
  double d1 = abs(cross(base, s1.p1 - s2.p1));
  double d2 = abs(cross(base, s1.p2 - s2.p1));
  double t = d1 / (d1 + d2);
  return s1.p1 + (s1.p2 - s1.p1) * t;
}
double getdistanceSS(Segment s1, Segment s2) {
  if (intersect(s1, s2)) return 0.0;
  return min(min(getdistanceSP(s1, s2.p1), getdistanceSP(s1, s2.p2)),
             min(getdistanceSP(s2, s1.p1), getdistanceSP(s2, s1.p2)));
}
pair<Point, Point> getcrosspoints(Circle c, Segment l) {
  Point pr = project(l, c.c);
  Point e = (l.p2 - l.p1) / abs(l.p2 - l.p1);
  double base = sqrt(c.r * c.r - norm(pr - c.c));
  return make_pair(pr + e * base, pr - e * base);
}
double arg(Point p) { return atan2(p.y, p.x); }
Point polar(double a, double r) { return Point(cos(r) * a, sin(r) * a); }
pair<Point, Point> getcrosspoints(Circle c1, Circle c2) {
  double d = abs(c1.c - c2.c);
  double a = acos((c1.r * c1.r + d * d - c2.r * c2.r) / (2 * c1.r * d));
  double t = arg(c2.c - c1.c);
  return make_pair(c1.c + polar(c1.r, t + a), c1.c + polar(c1.r, t - a));
}
int contains(vector<Point> g, Point p) {
  int n = g.size();
  bool x = false;
  for (int i = 0; i < n; i++) {
    Point a = g[i] - p, b = g[(i + 1) % n] - p;
    if (abs(cross(a, b)) < eps && dot(a, b) < eps) return 1;
    if (a.y > b.y) swap(a, b);
    if (a.y < eps && eps < b.y && cross(a, b) > eps) x = !x;
  }
  return (x ? 2 : 0);
}
vector<Point> andrewscan(vector<Point> s) {
  vector<Point> u, l;
  if (s.size() < 3) return s;
  sort(s.begin(), s.end());
  u.push_back(s[0]);
  u.push_back(s[1]);
  l.push_back(s[s.size() - 1]);
  l.push_back(s[s.size() - 2]);
  for (int i = 2; i < s.size(); i++) {
    for (int n = u.size(); n >= 2 && ccw(u[n - 2], u[n - 1], s[i]) != CLOCKWISE;
         n--) {
      u.pop_back();
    }
    u.push_back(s[i]);
  }
  for (int i = s.size() - 3; i >= 0; i--) {
    for (int n = l.size(); n >= 2 && ccw(l[n - 2], l[n - 1], s[i]) != CLOCKWISE;
         n--) {
      l.pop_back();
    }
    l.push_back(s[i]);
  }
  reverse(l.begin(), l.end());
  for (int i = u.size() - 2; i >= 1; i--) l.push_back(u[i]);
  return l;
}
int main(int argc, char const *argv[]) {
  int n;
  double ax, ay, bx, by, cx, cy, dx, dy;
  char ch;
  while (cin >> ax >> ch >> ay >> ch >> bx >> ch >> by >> ch >> cx >> ch >>
         cy >> ch >> dx >> ch >> dy) {
    Point a = Point(ax, ay);
    Point b = Point(bx, by);
    Point c = Point(cx, cy);
    Point d = Point(dx, dy);
    if (ccw(a, b, c) == ccw(b, c, d) && ccw(b, c, d) == ccw(c, d, a) &&
        ccw(c, d, a) == ccw(a, b, c)) {
      cout << "YES" << endl;
    } else {
      cout << "NO" << endl;
    }
  }
  return 0;
}
