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 FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

#define eps (1e-10)
struct Point{
    double x,y;
    Point(){}
    Point(double x,double y):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 k){return Point(x*k,y*k);}
    double norm(){return x*x+y*y;}
    double abs(){return sqrt(norm());}
    bool operator == (const Point &p) const{
    return fabs(x-p.x)<eps && fabs(y-p.y)<eps;
  }
  double dot(Point p){return x*p.x+y*p.y;}
  double det(Point p){return x*p.y-y*p.x;}
};
int ccw(Point a,Point b,Point c){
  Point t1=b-a,t2=c-a;
  if(t1.det(t2)> eps) return 1;//counter clockwise
  if(t1.det(t2)< -eps) return -1;//clockwise
  if(t1.dot(t2)< -eps) return 2;//c-a-b online
  if(t1.norm()<t2.norm()) return -2;//a-b-c online
  return 0;//a-c-b online
}
Point a[101];
int main(){
    int n;
    cin>>n;
    double x,y;
    rep(i,n){
        cin>>x>>y;
        a[i]=Point(x,y);
    }
    bool flag=true;
    rep(i,n){
        if(ccw(a[(i+1)%n],a[i],a[(i+2)%n])==1) flag=false;
    }
    cout<<flag<<endl;
    return 0;
}
