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| #include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
using namespace std;
typedef long long ll;
int n, m, c, T, uu[100005], vv[100005], tot, sta[2500005], din;
ll num[2500005];
const int dx[]={0, 1, 0, -1, 0};
const int dy[]={0, 0, -1, 0, 1};
ll f(int x, int y){
return (ll)(x-1)*m+y;
}
struct HashTable{
int cnt, mod, hea[1635955];
struct Edge{
ll x;
int y, nxt;
}edge[2500005];
void init(){
mod = 1635947;
memset(hea, 0, sizeof(hea));
cnt = 0;
}
void add(ll x, int y){
int p=x%mod;
for(int i=hea[p]; i; i=edge[i].nxt)
if(edge[i].x==x){
edge[i].y = y;
return ;
}
edge[++cnt].x = x; edge[cnt].y = y; edge[cnt].nxt = hea[p];
hea[p] = cnt;
}
int getV(ll x){
int p=x%mod;
for(int i=hea[p]; i; i=edge[i].nxt)
if(edge[i].x==x)
return edge[i].y;
return 0;
}
}hst;
struct Graph{
int hea[2500005], cnt, dfn[2500005], loo[2500005], idx, scc, bel[2500005];
vector<int> gee;
struct Edge{
int too, nxt;
}edge[10000005];
void init(){
cnt = idx = scc = 0;
gee.clear();
for(int i=1; i<=25*c; i++)
hea[i] = dfn[i] = 0;
}
void add_edge(int fro, int too){
edge[++cnt].nxt = hea[fro];
edge[cnt].too = too;
hea[fro] = cnt;
}
void tarjan(int x, int f){
bel[x] = scc;
dfn[x] = loo[x] = ++idx;
int cd=0;
for(int i=hea[x]; i; i=edge[i].nxt){
int t=edge[i].too;
if(!dfn[t]){
cd++;
tarjan(t, x);
loo[x] = min(loo[x], loo[t]);
if(f && loo[t]>=dfn[x]) gee.push_back(x);
}
else loo[x] = min(loo[x], dfn[t]);
}
if(!f && cd>=2) gee.push_back(x);
}
void dfs(int a, int b){
hst.add(f(a,b), 2);
for(int i=1; i<=4; i++){
int e=a+dx[i], g=b+dy[i];
if(e<1 || e>n || g<1 || g>m) continue;
int t=hst.getV(f(e,g));
if(t==3){
sta[++din] = lower_bound(num+1, num+1+tot, f(e,g))-num;
hst.add(f(e,g), 4);
}
else if(t==1) dfs(e, g);
}
}
}G;
bool chkFuYi(){
if((ll)n*m-c<=1) return true;
if((ll)n*m-c>2) return false;
for(int i=1; i<=n; i++)
for(int j=1; j<=m; j++){
if(hst.getV(f(i,j))!=1){
for(int k=1; k<=4; k++){
int a=i+dx[k], b=j+dy[k];
if(a<1 || a>n || b<1 || b>m) continue;
if(hst.getV(f(a,b))!=1) return true;
}
}
}
return false;
}
int main(){
cin>>T;
while(T--){
scanf("%d %d %d", &n, &m, &c);
tot = 0;
hst.init();
G.init();
for(int i=1; i<=c; i++){
scanf("%d %d", &uu[i], &vv[i]);
hst.add(f(uu[i],vv[i]), 1);
}
if(chkFuYi()){
printf("-1\n");
continue;
}
for(int i=1; i<=c; i++)
for(int j=-2; j<=2; j++)
for(int k=-2; k<=2; k++){
int a=uu[i]+j, b=vv[i]+k;
if(a<1 || a>n || b<1 || b>m) continue;
if(hst.getV(f(a, b))>=1) continue;
hst.add(f(a,b), 3);
num[++tot] = f(a,b);
}
sort(num+1, num+1+tot);
tot = unique(num+1, num+1+tot) - num - 1;
for(int i=1; i<=tot; i++){
int a=(num[i]-1)/m+1, b=(num[i]-1)%m+1;
for(int j=1; j<=4; j++){
int e=a+dx[j], g=b+dy[j];
if(e<1 || e>n || g<1 || g>m) continue;
if(hst.getV(f(e,g))!=3) continue;
G.add_edge(i, lower_bound(num+1, num+1+tot, f(e,g))-num);
}
}
for(int i=1; i<=tot; i++)
if(!G.dfn[i]){
G.scc++;
G.tarjan(i, 0);
}
bool flag=false;
for(int i=1; i<=c; i++){
din = 0;
if(hst.getV(f(uu[i],vv[i]))!=2)
G.dfs(uu[i], vv[i]);
for(int j=1; j<=din; j++)
if(G.bel[sta[1]]!=G.bel[sta[j]])
flag = true;
for(int j=1; j<=din; j++){
ll x=num[sta[j]];
hst.add(x, 3);
}
if(flag) break;
}
for(int i=1; i<=c; i++)
hst.add(f(uu[i],vv[i]),1);
if(flag){
printf("0\n");
continue;
}
if(n==1 || m==1){
printf("1\n");
continue;
}
for(int i=0; i<G.gee.size(); i++){
ll x=num[G.gee[i]];
int a=(x-1)/m+1, b=(x-1)%m+1;
for(int j=-1; j<=1; j++){
for(int k=-1; k<=1; k++){
int e=a+j, g=b+k;
if(e<1 || e>n || g<1 || g>m) continue;
if(hst.getV(f(e,g))==1){
flag = true;
break;
}
}
}
}
if(flag) printf("1\n");
else printf("2\n");
}
return 0;
}
|