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#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int ll
using PII = pair<int, int>;
template <typename T> using V = vector<T>;
template <typename T> using VV = vector<V<T>>;
template <typename T> using VVV = vector<VV<T>>;
#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define PB push_back
const ll INF = (1LL<<60);
const int MOD = 1000000007;
template <typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template <typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template <typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }
template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
out<<'('<<a.first<<','<<a.second<<')';
return out;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
out<<'[';
REP(i, a.size()) {out<<a[i];if(i!=a.size()-1)out<<',';}
out<<']';
return out;
}
int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};
V<int> g[1000010];
int d[1000010];
signed main(void)
{
cin.tie(0);
ios::sync_with_stdio(false);
int h, w;
cin >> h >> w;
VV<int> a(h, V<int>(w));
REP(i, h) REP(j, w) cin >> a[i][j], a[i][j]--;
REP(i, h) REP(j, w) {
REP(k, 4) {
int nx = j + dx[k], ny = i + dy[k];
if(IN(0LL,h,ny) && IN(0LL,w,nx) && a[i][j]>a[ny][nx]) {
g[a[i][j]].PB(a[ny][nx]);
}
}
}
int n = h*w;
function<int(int)> dfs = [&](int x) {
if(g[x].size()==0) return d[x]=x;
if(d[x]!=n) return d[x];
int ret = -2;
for(auto i: g[x]) {
int tmp = dfs(i);
if(ret == -2) ret = tmp;
else if(tmp != ret) ret = -1;
}
return d[x] = ret;
};
REP(i, n) d[i] = n;
REP(i, n) {
if(d[i]==n) {
dfs(i);
}
}
// REP(i, n) cout << d[i] << " ";
// cout << endl;
int ans = 0;
REP(i, n) if(d[i]==-1) ans++;
cout << ans << endl;
return 0;
}
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