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 ;

#define pb(n) push_back(n)
#define fi first
#define se second
#define all(r) begin(r),end(r)
#define vmax(ary) *max_element(all(ary))
#define vmin(ary) *min_element(all(ary))
#define debug(x) cout<<#x<<": "<<x<<endl
#define fcout(n) cout<<fixed<<setprecision((n))
#define scout(n) cout<<setw(n)
#define vary(type,name,size,init) vector< type> name(size,init)
#define vvl(v,w,h,init) vector<vector<ll>> v(w,vector<ll>(h,init))
#define mp(a,b) make_pair(a,b)

#define rep(i,n) for(int i = 0; i < (int)(n);++i)
#define REP(i,a,b) for(int i = (a);i < (int)(b);++i)
#define repi(it,array) for(auto it = array.begin(),end = array.end(); it != end;++it)
#define repa(n,array) for(auto &n :(array))

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) {//x????????????
      return real(a) != real(b) ? real(a) < real(b) : imag(a) < imag(b);
    }
    bool sorty(const P& a, const P& b) {//y????????????
      return imag(a) != imag(b) ? imag(a) < imag(b) : real(a) < real(b);
    }
  }
  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);
    }
  };

  typedef vector<P> G;

  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) {//3????????????????????§????????§??????????????????
    b -= a; c -= a;
    if (cross(b, c) > 0)   return +1;       // counter clockwise
    if (cross(b, c) < 0)   return -1;       // clockwise
    if (dot(b, c) < 0)     return +2;       // c--a--b on line
    if (norm(b) < norm(c)) return -2;       // a--b--c on line
    return 0;
  }
  bool is_convex(const G &g){
    if(g.size() == 3) return true;
    rep(i,g.size()){
      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;
  G g;
  rep(i,n){
    cin >> x >> y;
    g.push_back({x,y});
  }
  cout << is_convex(g) << endl;
  return 0;
}