//Huyduocdithitp
#include <bits/stdc++.h>
typedef long long ll;
#define endl '\n'
#define yes cout<<"YES"<<endl;
#define no cout<<"NO"<<endl;
#define fi first
#define se second
#define pii pair<ll, ll>
#define inf 1e18
#define faster ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define MP make_pair
#define TASK "ghuy4g"
#define start if(fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin);freopen(TASK".out","w",stdout);}
#define LOG 19
#define N 100005
using namespace std;
bool ghuy4g;
ll en_x, en_y, n;
ll d[N][2], st[6 * N], f[6 * N], m;
map<ll, ll> bit;
ll mx = 2e6 + 5, base = 1e6 + 1;
ll dist(ll x1, ll y1, ll x2, ll y2) {
return abs(x1 - x2) + abs(y1 - y2);
}
void lazy(ll id) {
if (f[id] == 0) return;
st[id] = f[id];
f[id * 2] = f[id];
f[id * 2 + 1] = f[id];
f[id] = 0;
}
void update(ll id, ll l, ll r, ll L, ll R, ll v) {
lazy(id);
if (l > R || r < L) return;
if (L <= l && r <= R) {
f[id] = v;
lazy(id);
return;
}
ll mid = (l + r) / 2;
update(id * 2, l, mid, L, R, v);
update(id * 2 + 1, mid + 1, r, L, R, v);
st[id] = st[id * 2] + st[id * 2 + 1];
}
ll get(ll id, ll l, ll r, ll i) {
lazy(id);
if (i > r || i < l) return 0;
if (l == r) return st[id];
ll mid = (l + r) / 2;
return get(id * 2, l, mid, i) + get(id * 2 + 1, mid + 1, r, i);
}
vector<ll> nenSo;
ll id(ll i) {
return lower_bound(nenSo.begin(), nenSo.end(), i) - nenSo.begin() + 1;
}
void upd(ll l, ll r, ll v) {
update(1, 1, m, id(l), id(r), v);
}
ll get(ll x) {
return get(1, 1, m, id(x));
}
struct vuong {
ll x1, y1, x2, y2;
} p[N];
bool cmp(vuong a, vuong b) {
return a.x2 < b.x2;
}
bool klinh;
signed main(void) {
faster;
cin >> en_x >> en_y;
nenSo.push_back(en_y);
cin >> n;
for (int i = 1; i <= n; i ++) {
cin >> p[i].x1 >> p[i].y1 >> p[i].x2 >> p[i].y2;
nenSo.push_back(p[i].y2);
nenSo.push_back(p[i].y1);
nenSo.push_back(p[i].y2 + 1);
nenSo.push_back(p[i].y1 - 1);
}
sort(p + 1, p + 1 + n, cmp);
sort(nenSo.begin(), nenSo.end());
nenSo.resize(unique(nenSo.begin(), nenSo.end()) - nenSo.begin());
m = nenSo.size();
for (int i = 1; i <= n; i ++) {
ll x1 = p[i].x1, x2 = p[i].x2, y1 = p[i].y1, y2 = p[i].y2;
//cout << i << " : " << x1 << " " << y1 << " " << x2 << " " << y2 << endl;
if (x2 > en_x) break;
// xet 2 diem
if (1) {
ll x = x2, y = y2 + 1;
ll xet = get(y);
if (xet == 0) {
d[i][0] = dist(0, 0, x, y);
}
else {
d[i][0] = min(dist(x, y, p[xet].x2, p[xet].y2 + 1) +d[xet][0], dist(x, y, p[xet].x2, p[xet].y1 - 1) +d[xet][1]);
}
}
if (1) {
ll x = x2, y = y1 - 1;
ll xet = get(y);
if (xet == 0) {
d[i][1] = dist(0, 0, x, y);
}
else {
d[i][1] = min(dist(x, y, p[xet].x2, p[xet].y2 + 1) +d[xet][0], dist(x, y, p[xet].x2, p[xet].y1 - 1) +d[xet][1]);
}
}
upd(y1, y2, i);
}
ll xet = get(en_y);
//cout << "xet: " << xet << endl;
if (xet == 0) {
cout << dist(0, 0, en_x, en_y) << endl;
return 0;
cout << 2 << endl;
cout << 0 << " " << en_x << endl;
cout << en_y << " " << 0 << endl;
}
else {
cout << min(dist(en_x, en_y, p[xet].x2, p[xet].y2 + 1) + d[xet][0],
dist(en_x, en_y, p[xet].x2, p[xet].y1 - 1) + d[xet][1]) << endl;
}
cerr << fabs(&klinh - &ghuy4g) / 1048576.0;
return 0;
}
