#include <iostream>h>

using namespace std;
 
void checkTriangle(int x1, int y1, int x2,
                   int y2, int x3, int y3)
{
 
    int a = x1 * (y2 - y3)
            + x2 * (y3 - y1)
            + x3 * (y1 - y2);
 
    if (a == 0)
        cout << "No";
    else
        cout << "Yes";
}
 
int main()
{
    int x1 = 1, x2 = 1, x3 = 2,
        y1 = 1, y2 = 6, y3 = 5;
    checkTriangle(x1, y1, x2,
                  y2, x3, y3);
    
}