View Code of Problem 67

#include<iostream>

using namespace std;

int main(){
	
	double x1, y1, x2, y2, x3, y3, x4, y4;
	
	double k1, k2;
	
	double b1, b2;
	
	while(cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4){
		if(x1==x2 && x3==x4 && x1==x3)
			cout<<"Yes"<<endl;
		else if(x1==x2 && x3==x4 && x1!=x3)
			cout<<"No"<<endl;
		else if(x1==x2&&x3!=x4)
			cout<<"Yes"<<endl;
		else if(x1!=x2&&x3==x4)
			cout<<"Yes"<<endl;
		else{
			k1=(y2-y1)/(1.0*(x2-x1));
			k2=(y4-y3)/(1.0*(x4-x3));
			b1=y1-k1*x1;
			b2=y3-k2*x3;
			if(k1==k2&&b1!=b2)
				cout<<"No"<<endl;
			else
				cout<<"Yes"<<endl;
		}		
	}
	
	return 0;
}