#include <cstdio>
#include <cassert>
#include <cstring>
#include <algorithm>
using namespace std;

const int maxn = 100 * 2 + 5;
const int maxv = 10000 + 5;
const int RIGHT = 0;
const int UP = 1;

int line[maxn][maxn][2]; // RIGHT and UP
int alive[maxn][maxn];   // alive[x][y] == 1 iff the square whose left-bottom corner is (x,y), is alive

int npx, npy; // number of points in x and y directions. points are numbered 1 to np*. squares are numbered 0 to np*
int xp[maxn], yp[maxn], idx[maxv], idy[maxv]; // xp[idx[v]] = v.

void dfs(int x, int y) {
    if (alive[x][y]) return;
    alive[x][y] = 1;
    if (y < npy && !line[x][y + 1][RIGHT]) dfs(x, y + 1); // UP
    if (y > 0 && !line[x][y][RIGHT]) dfs(x, y - 1);       // DOWN
    if (x > 0 && !line[x][y][UP]) dfs(x - 1, y);          // LEFT
    if (x < npx && !line[x + 1][y][UP]) dfs(x + 1, y);    // RIGHT
}

int main() {
    int T;
    while (cin>>T&&T!= 0) {
        int n, x1[maxn], y1[maxn], x2[maxn], y2[maxn], vis[maxv];
        scanf("%d", &n);
        for (int i = 0; i < n; i++) {
            scanf("%d%d%d%d", &x1[i], &y1[i], &x2[i], &y2[i]);
            if (x1[i] == x2[i]) {
                assert(y1[i] != y2[i]);
                if (y1[i] > y2[i]) swap(y1[i], y2[i]);
            } else {
                assert(y1[i] == y2[i]);
                if (x1[i] > x2[i]) swap(x1[i], x2[i]);
            }
        }

        // discrete x
        memset(vis, 0, sizeof(vis));
        for (int i = 0; i < n; i++) vis[x1[i]] = vis[x2[i]] = 1;
        npx = 0;
        for (int i = 0; i < maxv; i++) {
            if (vis[i]) {
                xp[++npx] = i;
                idx[i] = npx;
            }
        }

        // discrete y
        memset(vis, 0, sizeof(vis));
        for (int i = 0; i < n; i++) vis[y1[i]] = vis[y2[i]] = 1;
        npy = 0;
        for (int i = 0; i < maxv; i++) {
            if (vis[i]) {
                yp[++npy] = i;
                idy[i] = npy;
            }
        }

        // draw lines in discrete grid
        memset(line, 0, sizeof(line));
        for (int i = 0; i < n; i++) {
            if (x1[i] != x2[i]) {
                for (int x = idx[x1[i]]; x < idx[x2[i]]; x++) {
                    line[x][idy[y1[i]]][RIGHT] = 1;
                }
            }
            if (y1[i] != y2[i]) {
                for (int y = idy[y1[i]]; y < idy[y2[i]]; y++) {
                    line[idx[x1[i]]][y][UP] = 1;
                }
            }
        }

        // floodfill
        memset(alive, 0, sizeof(alive));
        dfs(0, 0);

        // accumulate answer
        int ans = 0;
        int lost = 0;
        for (int x = 1; x <= npx; x++) {
            for (int y = 1; y <= npy; y++) {
                if (!alive[x][y]) lost++;
                if (line[x][y][RIGHT] && (alive[x][y] || alive[x][y - 1])) {
                    ans += xp[x + 1] - xp[x]; // check RIGHT
                }
                if (line[x][y][UP] && (alive[x][y] || alive[x - 1][y])) {
                    ans += yp[y + 1] - yp[y]; // check UP
                }
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}