10078

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

struct Point{
int x;
int y;
}P;
vector<Point> vb,vb1;
int used[100];

bool cmp(Point a,Point b)
{
if(a.x!=b.x)
return a.x<b.x;
else
return a.y<b.y;
}

int ccw(Point a,Point b,Point c)
{
int p = a.x*b.y - a.x*c.y - a.y*b.x + a.y*c.x + b.x*c.y - c.x * b.y;
if(p>0)
return 1;
else
return 0;
}

int main()
{
int N,a,b;

while(cin>>N)
{
if(N==0)
break;
vb.clear();
for(int i=0;i<N;i++)
{
cin>>a>>b;
P.x=a;
P.y=b;
used[i]=0;
vb.push_back(P);
}

fill(used,used+N,0);
if(N<=3)
{
cout<<"No\n";
continue;
}
sort(vb.begin(),vb.end(),cmp);

vb1.clear();

vb1.push_back(vb[0]);
used[0]=1;

for(int i=0;i<(N-1);i++)
{
int next;
for(int j=1;j<N;j++)
{
if(used[j]==0)
{
next=j;
break;
}
}

for(int j=1;j<N;j++)
{
if(used[j]==0 && ccw(vb1[i],vb[next],vb[j])==0)
next = j;
}
vb1.push_back(vb[next]);
used[next]=1;
}

vb1.push_back(vb1[0]);
vb1.push_back(vb1[1]);

int f=0;
for(int i=0;i+2<vb1.size();i++)
{
if(ccw(vb1[i],vb1[i+1],vb1[i+2])==0)
{
cout<<"Yes\n";
f=1;
break;
}
}
if(f==0)cout<<"No\n";
}

return 0;
}