#include<iostream>
using namespace std;
int main()
{
int x1, y1, x2, y2, x3, y3, x4, y4;
cin >> x1 >> y1
>> x2 >> y2
>> x3 >> y3
>> x4 >> y4;
if (x1 == x2 || x3 == x4)
{
cout << "YES!";
}
else
{
double M1 = (double)(y2 - y1) / (x2 - x1);
double M2 = (double)(y4 - y3) / (x4 - x3);
if (M1 != M2)
{
cout << "YES!";
}
else
{
cout << "NO";
}
}
return 0;
}
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