#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

struct Line {
    int x, l, r;
    bool operator < (const Line& line) const {
        if (x != line.x) return x < line.x;
        else if (l != line.l) return l < line.l;
        return r < line.r;
    }
};
vector<Line> cols, rows;

void merge(vector<Line>& v)
{
    if (v.size() == 0) return ;
    sort(v.begin(), v.end());
    vector<Line> res;

    int pre_x = v[0].x;
    int l = v[0].l, r = v[0].r;
    for (int i = 1; i < v.size(); ++i)
    {
        if (v[i].x != pre_x || v[i].l > r) 
        {
            res.push_back({pre_x, l, r});
            pre_x = v[i].x, l = v[i].l, r = v[i].r;
        }
        else r = max(r, v[i].r);
    }

    res.push_back({pre_x, l, r});
    v = res;
}

int main()
{
    int n;
    cin >> n;
    for (int i = 1; i <= n; ++i)
    {
        int x1, x2, y1, y2;
        cin >> x1 >> y1 >> x2 >> y2;
        if (x1 == x2) rows.push_back({x1, min(y1, y2), max(y1, y2)});
        else cols.push_back({y1, min(x1, x2), max(x1, x2)});
    }

    long long res = 0;
    merge(rows), merge(cols);

    for (auto &t : rows) res += (t.r - t.l + 1);
    for (auto &t : cols) res += (t.r - t.l + 1);

    for (auto &row : rows) 
        for (auto &col : cols)
        {
            if (row.x >= col.l && row.x <= col.r && col.x >= row.l && col.x <= row.r) --res;
        }

    cout << res << endl;
    return 0;
}