mn

#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;

double vectorProd(double x1,double y1,double x2,double y2){
    return x1*y2 - x2*y1;
}

bool signsIsDifferent(double a,double b){
    return a <= 0 && b >= 0 || a >= 0 && b <= 0;
}


struct Point{
    double x = .0,y = .0;
    double distanceTo(Point point){
        return sqrt(sqrt((point.x - x)*(point.x - x) + (point.y - y)*(point.y - y)));
    }
    bool operator == (const Point &point) const {
        return this->x == point.x && this->y == point.y;
    }
};

struct Line{
  Point l,r;
  bool isParallelTo(Line line){
      double x1 = r.x - l.x;
      double y1 = r.y - l.y;
      double x2 = line.r.x - line.l.x;
      double y2 = line.r.y - line.l.y;
      return (abs(vectorProd(x1,y1,x2,y2)) < 1e-8);
  }
  bool isCrossesTo(Line line){
      Point l1 = line.l;
      Point r1 = line.r;
      double v1 = vectorProd(l1.x - l.x,l1.y - l.y,r.x - l.x,r.y - l.y);
      double v2 = vectorProd(r1.x - l.x,r1.y - l.y,r.x - l.x,r.y - l.y);
      double v3 = vectorProd(r.x - r1.x,r.y - r1.y,l1.x - r1.x, l1.y - r1.y);
      double v4 = vectorProd(l.x - r1.x,l.y - r1.y,l1.x - r1.x, l1.y - r1.y);
      int c = (v1 == 0) + (v2 == 0) + (v3 == 0) + (v4 == 0);
      if(l1 == l || r1 == l || l1 == r || r1 == r){
          return 1;
      }
      if(c == 4){
          if(l.distanceTo(r1) + r1.distanceTo(r) == l.distanceTo(r) || l1.distanceTo(r) + r.distanceTo(r1) == l1.distanceTo(r1))return 1;
      }
      return signsIsDifferent(v1,v2) && signsIsDifferent(v3,v4);
  }
};


int howAreTheLines(Line l1,Line l2){
    if(l1.isParallelTo(l2) && l1.isCrossesTo(l2)) return 2;
    if(l1.isParallelTo(l2)) return 1;
    if(l1.isCrossesTo(l2)) return -1;
    return 0;
}

int main(){
    int n;
    cin >> n;
    Line * arr = new Line[n];
    for(int i = 0;i < n;++i){
        cout << "Введите координаты начала и конца отрезка\n";
        Point p1,p2;
        cin >> p1.x >> p1.y >> p2.x >> p2.y;
        Line line;
        line.l = p1;
        line.r = p2;
        arr[i] = line;
    }
    for(int i = 0;i < n;++i){
        for(int j = i+1;j < n;++j){
            int ans = howAreTheLines(arr[i],arr[j]);
            if(ans == 2) cout << "Отрезки " << i+1 << " и " << j+1 << " пересекаются и паралельны\n";
            else if(ans == -1)cout << "Отрезки " << i+1 << " и " << j+1 << " пересекаются\n";
            else if(ans == 1) cout << "Отрезки " << i+1 << " и " << j+1 << " параллельны\n";
            else cout << "Отрезки " << i+1 << " и " << j+1 << " ни пересекаются, ни параллельны\n";
        }
    }
    return 0;
}