/* https://oj.uz/submission/100855 (Benq) */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define NU 30000
#define NV 2000
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
int nu, nv;
int *eu[NV], eo[NV], el[NV], er[NV];
int uu[NV], vv[NU]; char visited[NV];
void append(int v, int u) {
int o = eo[v]++;
if (o >= 2 && (o & o - 1) == 0)
eu[v] = (int *) realloc(eu[v], o * 2 * sizeof *eu[v]);
eu[v][o] = u;
}
void sort(int *ii, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;
while (j < k)
if (ii[j] == i_)
j++;
else if (ii[j] < i_) {
tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
i++, j++;
} else {
k--;
tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
}
sort(ii, l, i);
l = k;
}
}
int dfs(int v) {
int o;
if (visited[v])
return 0;
visited[v] = 1;
for (o = el[v]; o < er[v]; o++) {
int u = eu[v][o], w = vv[u];
if (w == -1 || dfs(w)) {
uu[v] = u, vv[u] = v;
return 1;
}
}
return 0;
}
int check() {
int v;
for (v = 0; v < nv; v++)
if (uu[v] == -1) {
memset(visited, 0, nv * sizeof *visited);
if (!dfs(v))
return 0;
}
return 1;
}
int main() {
int m, h, l, r, u, v, ans;
scanf("%d%d%d", &nu, &nv, &m);
for (v = 0; v < nv; v++)
eu[v] = (int *) malloc(2 * sizeof *eu[v]);
for (h = 0; h < m; h++) {
scanf("%d%d", &u, &v), u--, v--;
append(v, u);
}
for (v = 0; v < nv; v++)
sort(eu[v], 0, eo[v]);
memset(uu, -1, nv * sizeof *uu), memset(vv, -1, nu * sizeof *vv);
ans = 0;
for (l = 0, r = -1; l < nu; l++) {
while (r < nu && !check()) {
r++;
for (v = 0; v < nv; v++)
if (er[v] < eo[v] && eu[v][er[v]] == r)
er[v]++;
}
ans += nu - r;
for (v = 0; v < nv; v++) {
if (el[v] < eo[v] && eu[v][el[v]] == l)
el[v]++;
if (uu[v] == l)
uu[v] = -1;
}
}
printf("%d\n", ans);
return 0;
}
