#include <bits/stdc++.h>
using namespace std;
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 = 0, double y = 0) : x(x), y(y) {}
  Point operator+(Point p) { return Point(x + p.x, y + p.y); }
  Point operator-(Point p) { return Point(x - p.x, y - p.y); }
  Point operator*(double a) { return Point(a * x, a * y); }
  Point operator/(double a) { return Point(x / a, y / a); }
  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) < (1e-10) && fabs(y - p.y) < (1e-10);
  }
};
struct Circle {
  Point c;
  double r;
};
struct seg {
  Point p1, p2;
};
double norm(Point p) { return p.x * p.x + p.y * p.y; }
double abs(Point p) { return sqrt(norm(p)); }
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; }
bool C90(seg s1, seg s2) {
  return (fabs((dot(s1.p2 - s1.p1, s2.p2 - s2.p1)) - (0.0)) < (1e-10));
}
bool C0(seg s1, seg s2) {
  return (fabs((cross(s1.p2 - s1.p1, s2.p2 - s2.p1)) - (0.0)) < (1e-10));
}
Point project(seg s, Point p) {
  Point base = s.p2 - s.p1;
  double r = dot(p - s.p1, base) / norm(base);
  return s.p1 + base * r;
}
Point reflection(seg s, Point p) { return p + (project(s, p) - p) * 2.0; }
double getDistancePP(Point a, Point b) { return abs(a - b); }
double getDistanceLP(seg l, Point p) {
  return abs(cross(l.p2 - l.p1, p - l.p1) / abs(l.p2 - l.p1));
}
double getDistanceSP(seg 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) > (1e-10)) return COUNTER_CLOCKWISE;
  if (cross(a, b) < -(1e-10)) return CLOCKWISE;
  if (dot(a, b) < -(1e-10)) return ONLINE_BACK;
  if (norm(a) < norm(b)) 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(seg s1, seg s2) { return intersect(s1.p1, s1.p2, s2.p1, s2.p2); }
bool squareintersect(seg s1, seg s2) {
  if (s1.p2.x < s2.p1.x || s2.p2.x < s1.p1.x) return 0;
  if (s1.p2.y < s2.p1.y || s2.p2.y < s1.p1.y) return 0;
  return 1;
}
double getDistance(seg s1, seg 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)));
}
Point getCrossPoint(seg s1, seg 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;
}
seg getCrossPoint(Circle c, seg 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));
  seg pp;
  pp.p1 = (pr + e * base);
  pp.p2 = (pr - e * base);
  return pp;
}
double dot(complex<double> a, complex<double> b) { return real(b * conj(a)); }
double cross(complex<double> a, complex<double> b) { return imag(b * conj(a)); }
double Area(vector<complex<double> > &a) {
  double b = 0;
  int n = a.size();
  for (int i = 0; i < n; i++) b += cross(a[i], a[(i + 1 == n ? 0 : i + 1)]);
  return abs(b / 2.0);
}
int intersectCC(Circle a, Circle b) {
  double dist = abs(a.c - b.c);
  if (dist > a.r + b.r + (1e-10)) return 4;
  if (dist > a.r + b.r - (1e-10)) return 3;
  if (dist > abs(a.r - b.r) + (1e-10)) return 2;
  if (dist > abs(a.r - b.r) - (1e-10)) return 1;
  return 0;
}
seg scan() {
  seg a;
  scanf("%lf%lf%lf%lf", &a.p1.x, &a.p1.y, &a.p2.x, &a.p2.y);
  return a;
}
int main() {
  Point a, b, c, d;
  while (scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf", &a.x, &a.y, &b.x, &b.y, &c.x,
               &c.y, &c.x, &c.y) != EOF) {
    int q1 = CCW(a, c, b), q2 = CCW(b, d, c), q3 = CCW(c, a, d),
        q4 = CCW(d, b, a), q = CCW(a, c, b);
    if (q == 1) {
      if (q1 == 1 && q2 == 1 && q3 == 1 && q4 == 1)
        cout << "YES" << endl;
      else
        cout << "NO" << endl;
    } else {
      if (q1 == -1 && q2 == -1 && q3 == -1 && q4 == -1)
        cout << "YES" << endl;
      else
        cout << "NO" << endl;
    }
  }
}
