#include <cstdio>#include <algorithm>#include <cstring>#include <vector>using namespace std;#define lson rt << 1 , l , mid#define rson rt << 1 | 1, mid + 1 , rconst int maxn = 10000 + 10;int cnt[maxn << 2], len[maxn << 2], n;struct Seg {	int x, l, r, cover;	Seg(int x, int l, int r, int cover) :x(x), l(l), r(r), cover(cover) {}	bool operator < (const Seg &seg) const {		if (x == seg.x) return cover > seg.cover;		return x < seg.x;	}};vector<Seg> seg;vector<int> num;int sx1[maxn], sy1[maxn], sx2[maxn], sy2[maxn];void pushup(int rt, int l, int r) {	if (cnt[rt]) len[rt] = num[r + 1] - num[l];	else if (l == r) len[rt] = 0;	else len[rt] = len[rt << 1] + len[rt << 1 | 1];}void update(int rt, int l, int r, int ql, int qr, int Val) {	if (ql <= l && qr >= r) {		cnt[rt] += Val; pushup(rt, l, r);	}	else {		int mid = (l + r) >> 1;		if (ql <= mid) update(lson, ql, qr, Val);		if (qr > mid) update(rson, ql, qr, Val);		pushup(rt, l, r);	}}int GetID(int val) {	return lower_bound(num.begin(), num.end(), val) - num.begin();}int solve(int px1[], int py1[], int px2[], int py2[]) {	seg.clear(); num.clear();	memset(cnt, 0, sizeof(cnt));	memset(len, 0, sizeof(len));	for (int i = 0; i < n; i++) {		seg.push_back(Seg(px1[i], py1[i], py2[i], 1));		seg.push_back(Seg(px2[i], py1[i], py2[i], -1));		num.push_back(py1[i]);		num.push_back(py2[i]);	}	sort(seg.begin(), seg.end());	sort(num.begin(), num.end());	num.erase(unique(num.begin(), num.end()), num.end());	int ret = 0, msize = seg.size(), nowlen = 0, k = num.size();	for (int i = 0; i < msize; i++) {		int ql = GetID(seg[i].l), qr = GetID(seg[i].r) - 1;		update(1, 0, k - 1, ql, qr, seg[i].cover);		ret += abs(nowlen - len[1]);		nowlen = len[1];	}	return ret;}int main() {	while (scanf("%d", &n) != EOF) {		for (int i = 0; i < n; i++) {			scanf("%d%d%d%d", &sx1[i], &sy1[i], &sx2[i], &sy2[i]);		}		int ret = solve(sx1, sy1, sx2, sy2) + solve(sy1, sx1, sy2, sx2);		printf("%d\n", ret);	}}

#include <cstdio>#include <cstring>#include <algorithm>#include <vector>#include <climits>using namespace std;const int maxn = 2e4 + 10;#define lson rt << 1, l, mid#define rson rt << 1 | 1,mid + 1,rstruct Seg {	int l, r, x, cover;	Seg(int l, int r, int x, int cover) :l(l), r(r), x(x), cover(cover) {}	bool operator < (const Seg &seg) const {		if (x == seg.x) return cover > seg.cover;		return x < seg.x;	}};vector<Seg> seg;int n;bool lbound[maxn << 2], rbound[maxn << 2];int numseg[maxn << 2], len[maxn << 2], cnt[maxn << 2];int minval, maxval;void pushup(int rt, int l, int r) {	int lc = rt << 1, rc = rt << 1 | 1;	if (cnt[rt]) {		lbound[rt] = rbound[rt] = true;		//因为每一条线段的长度都等于1，第l条线段起始点是l，第r条线段的结束点是r + 1,长度是r + 1 - l		len[rt] = r - l + 1;		//因为横向必定有两条边，所以为2		numseg[rt] = 2;	}	else if (l == r) {		len[rt] = numseg[rt] = lbound[rt] = rbound[rt] = 0;	}	else {		len[rt] = len[lc] + len[rc];		lbound[rt] = lbound[lc];		rbound[rt] = rbound[rc];		numseg[rt] = numseg[lc] + numseg[rc];		//如果在交点重合		if (rbound[lc] && lbound[rc]) {			numseg[rt] -= 2;		}	}}void update(int rt, int l, int r, int ql, int qr, int Val) {	if (ql <= l && qr >= r) {		cnt[rt] += Val;		pushup(rt, l, r);	}	else {		int mid = (l + r) >> 1;		if (ql <= mid) update(lson, ql, qr, Val);		if (qr > mid) update(rson, ql, qr, Val);		pushup(rt, l, r);	}}int main() {	while (scanf("%d", &n) != EOF) {		seg.clear();		minval = INT_MAX; maxval = -1;		for (int i = 1; i <= n; i++) {			int x1, y1, x2, y2;			scanf("%d%d%d%d", &x1, &y1, &x2, &y2);			seg.push_back(Seg(y1, y2, x1, 1));			seg.push_back(Seg(y1, y2, x2, -1));			minval = min(minval, min(y1, y2));			maxval = max(maxval, max(y1, y2));		}		sort(seg.begin(), seg.end());		int msize = seg.size(), ret = 0, last = 0;		for (int i = 0; i < msize; i++) {			if (seg[i].l < seg[i].r) update(1, minval, maxval, seg[i].l, seg[i].r - 1, seg[i].cover);			//横向的长度			if (i < msize - 1) ret += numseg[1] * (seg[i + 1].x - seg[i].x);			//纵向的长度			ret += abs(last - len[1]);			last = len[1];		}		printf("%d\n", ret);	}	return 0;}