#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define se second
#define fi first
#define ll long long
#define ii pair<int, int>
const long mxN = 1e5 + 7, inf = 1e9 + 7;
int nRow, nCol, n, cnt[mxN * 4], lazy[mxN * 4], dsu[mxN];
ii u[mxN], v[mxN], tree[mxN * 4];
map<int, int> m[mxN * 4];
vector<int> hor[mxN], ver[mxN], Col, Row;
void Build(int j = 1, int l = 0, int r = Col.size() - 1)
{
lazy[j] = -1;
if (l == r)
{
tree[j] = {inf, l};
return;
}
int mid = (l + r) / 2;
Build(j * 2, l, mid);
Build(j * 2 + 1, mid + 1, r);
tree[j] = min(tree[j * 2], tree[j * 2 + 1]);
}
void Ers(int j)
{
for (ii i : m[j])
{
int tmp = j / 2;
while (tmp)
{
m[tmp][i.fi] -= i.se;
if (!m[tmp][i.fi])
m[tmp].erase(i.fi);
tmp /= 2;
}
}
m[j].clear();
}
void Down(int j)
{
if (lazy[j] == -1)
return;
for (int u = 0; u <= 1; u++)
{
lazy[j * 2 + u] = lazy[j];
m[j * 2 + u].clear();
if (cnt[j * 2 + u])
m[j * 2 + u][lazy[j]] = cnt[j * 2 + u];
}
lazy[j] = -1;
}
void Cut(int vt, int j = 1, int l = 0, int r = Col.size() - 1)
{
if (l > vt || vt > r)
return;
cnt[j]--;
if (l == r)
{
tree[j].fi = inf;
Ers(j);
return;
}
Down(j);
int mid = (l + r) / 2;
Cut(vt, j * 2, l, mid);
Cut(vt, j * 2 + 1, mid + 1, r);
tree[j] = min(tree[j * 2], tree[j * 2 + 1]);
}
void Upd(int vt, int h, int val, int j = 1, int l = 0, int r = Col.size() - 1)
{
if (l > vt || vt > r)
return;
cnt[j]++;
m[j][val]++;
tree[j] = min(tree[j], {h, vt});
if (l == r)
return;
Down(j);
int mid = (l + r) / 2;
Upd(vt, h, val, j * 2, l, mid);
Upd(vt, h, val, j * 2 + 1, mid + 1, r);
}
int Find(int j)
{
if (dsu[j] == j)
return j;
else
return dsu[j] = Find(dsu[j]);
}
bool Union(int u, int v)
{
u = Find(u);
v = Find(v);
if (u == v)
return 0;
dsu[v] = u;
return 1;
}
int mem;
int Get(int u, int v, int id, int j = 1, int l = 0, int r = Col.size() - 1)
{
if (u > Col[r] || Col[l] > v || !cnt[j])
return 0;
if (u <= Col[l] && Col[r] <= v)
{
lazy[j] = id;
for (ii i : m[j])
mem += Union(id, i.fi);
Ers(j);
m[j][id] = cnt[j];
return cnt[j];
}
Down(j);
int mid = (l + r) / 2;
int res = Get(u, v, id, j * 2, l, mid) + Get(u, v, id, j * 2 + 1, mid + 1, r);
if (res)
m[j][id] = res;
return res;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
cin >> nRow >> nCol >> n;
// Nen bang
Row.push_back(0);
Row.push_back(nRow);
Col.push_back(0);
Col.push_back(nCol);
for (int i = 1; i <= n; i++)
{
cin >> u[i].fi >> u[i].se >> v[i].fi >> v[i].se;
Row.push_back(u[i].fi);
// Chi nen cot
if (u[i].se == v[i].se)
Col.push_back(v[i].se);
}
sort(Row.begin(), Row.end());
Row.erase(unique(Row.begin(), Row.end()), Row.end());
sort(Col.begin(), Col.end());
Col.erase(unique(Col.begin(), Col.end()), Col.end());
// Tao thu tu Sweepline
n++;
u[n] = {nRow, 0};
v[n] = {nRow, nCol};
for (int i = 1; i <= n; i++)
{
dsu[i] = i;
int j = lower_bound(Row.begin(), Row.end(), u[i].fi) - Row.begin();
if (u[i].fi == v[i].fi)
hor[j].push_back(i);
else
ver[j].push_back(i);
}
Build();
Upd(0, nRow, 0);
Upd(Col.size() - 1, nRow, 0);
ll ans = 0;
for (int i = 0; i < Row.size(); i++)
{
// Cat doan het
while (tree[1].fi < Row[i])
Cut(tree[1].se);
// Upd doan doc
for (int j : ver[i])
Upd(lower_bound(Col.begin(), Col.end(), u[j].se) - Col.begin(), v[j].fi, j * (i != 0));
// Upd doan ngang
for (int j : hor[i])
{
mem = 0;
ans += Get(u[j].se, v[j].se, j) - mem;
}
}
cout << ans;
}
