For a given polygon g, print "1" if g is a convex polygon, "0" otherwise. Here, in a convex polygon, all interior angles are less than or equal to 180 degrees.

g is represented by a sequence of points p1, p2,..., pn where line segments connecting pi and pi+1 (1 ≤ i ≤ n-1) are sides of the polygon. The line segment connecting pn and p1 is also a side of the polygon.

Constraints

* 3 ≤ n ≤ 100
* -10000 ≤ xi, yi ≤ 10000
* No point of the polygon will occur more than once.
* Two sides of the polygon can intersect only at a common endpoint.

Input

g is given by coordinates of the points p1,..., pn in the following format:


n
x1 y1
x2 y2
:
xn yn


The first integer n is the number of points. The coordinate of a point pi is given by two integers xi and yi. The coordinates of points are given in the order of counter-clockwise visit of them.

Output

Print "1" or "0" in a line.

Examples

Input

4
0 0
3 1
2 3
0 3


Output

1


Input

5
0 0
2 0
1 1
2 2
0 2


Output

0
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename T>
void O(T t) {
  cout << t << endl;
}
const double EPS = 1e-8;
const double INF = 1e12;
typedef complex<double> P;
namespace std {
bool operator<(const P& a, const P& b) {
  return real(a) != real(b) ? real(a) < real(b) : imag(a) < imag(b);
}
bool sorty(const P& a, const P& b) {
  return imag(a) != imag(b) ? imag(a) < imag(b) : real(a) < real(b);
}
}  // namespace std
double cross(const P& a, const P& b) { return imag(conj(a) * b); }
double dot(const P& a, const P& b) { return real(conj(a) * b); }
struct L : public vector<P> {
  L(){};
  L(const P& a, const P& b) {
    push_back(a);
    push_back(b);
  }
};
struct C {
  P p;
  double r;
  C(){};
  C(const P& p, double r) : p(p), r(r) {}
};
int ccw(P a, P b, P c) {
  b -= a;
  c -= a;
  if (cross(b, c) > 0) return +1;
  if (cross(b, c) < 0) return -1;
  if (dot(b, c) < 0) return +2;
  if (norm(b) < norm(c)) return -2;
  return 0;
}
bool is_convex(const vector<P>& g) {
  for (int i = 0; i < (int)(g.size()); ++i) {
    if (ccw(g[i], g[(i + 1) % g.size()], g[(i + 2) % g.size()]) != 1 &&
        ccw(g[i], g[(i + 1) % g.size()], g[(i + 2) % g.size()]) != -2) {
      return false;
    }
  }
  return true;
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n;
  double x, y;
  cin >> n;
  vector<P> g;
  for (int i = 0; i < (int)(n); ++i) {
    cin >> x >> y;
    g.push_back({x, y});
  }
  cout << is_convex(g) << endl;
  return 0;
}
