jabuke.cpp

#include <iostream>
#include <vector>

using namespace std;

struct point {
    int x;
    int y;
};

double getarea(point p1, point p2, point p3) {
    vector<point> v = {p1, p2, p3};

    double a = 0;
    for(int i = 0, j = 1; i < 3; i++, j = (j+1)%3) {
        a += v[i].x * v[j].y;
        a -= v[j].x * v[i].y;
    }

    return a / 2;
}

bool left(point p1, point p2, point p3) {
    return ((p2.x - p1.x)*(p3.y-p1.y) - (p2.y-p1.y)*(p3.x - p1.x)) >= 0;
}

int main() {
    point p1, p2, p3;
    cin >> p1.x >> p1.y;
    cin >> p2.x >> p2.y;
    cin >> p3.x >> p3.y;

    int points;
    cin >> points;

    double area = getarea(p1, p2, p3);

    if(area < 0) {
        swap(p3, p1);
        area = -area;
    }

    cout << fixed;
    cout.precision(1);
    cout << area << endl;

    int total = 0;
    while(points--) {
        point temp;
        cin >> temp.x >> temp.y;

        if(left(p1, p2, temp) && left(p2, p3, temp) && left(p3, p1, temp)) {
            total++;
        }
    }

    cout << total << endl;
}