#include <bits/stdc++.h>
//#include<boost/multiprecision/cpp_int.hpp>
//#include<boost/multiprecision/cpp_dec_float.hpp>
//#include <atcoder/all>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a; i >-1; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a; i > b; --i)
#define repl(i, a) for (ll i = (ll)0; i < (ll)a; ++i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define fi first
#define se second
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll mod_998244353 = 998244353;
constexpr ll INF = 1LL << 60;

// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

//using lll=boost::multiprecision::cpp_int;
//using Double=boost::multiprecision::number<boost::multiprecision::cpp_dec_float<128>>;//仮数部が1024桁
template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

ll mypow(ll x, ll n, const ll &p = -1)
{ //x^nをmodで割った余り

	if (p != -1)
	{
		x =(x%p+p)%p;
	}
	ll ret = 1;
	while (n > 0)
	{
		if (n & 1)
		{
			if (p != -1)
				ret = (ret * x) % p;
			else
				ret *= x;
		}
		if (p != -1)
			x = (x * x) % p;
		else
			x *= x;
		n >>= 1;
	}
	return ret;
}

using namespace std;
//using namespace atcoder;

void solve()
{	
	int h,w;
	cin>>h>>w;

	vector<vector<int>>a(h,vector<int>(w));
	rep(i,h)rep(j,w)cin>>a[i][j];
	vector<vector<int>>b(w,vector<int>(h));
	rep(i,h)rep(j,w)b[j][i]=a[i][j];
	ll ans=0;
	{
		rep(i,h){
			unordered_set<int>ust;
			rep(j,w){
				if(a[i][j]){
					if(ust.count(a[i][j])){
						a[i][j]=0;
						continue;
					}
					bool ok=false;
					rep(k,h){
						if(k==i)continue;
						if(a[k][j]==a[i][j]){
							ok=true;
							break;
						}
					}
					if(!ok){
						ust.emplace(a[i][j]);
						a[i][j]=0;
						++ans;
					}
				}
			}
			rep(j,w){
				if(ust.count(a[i][j]))a[i][j]=0;
			}
		}
		vector<vector<int>>c(w,vector<int>(h));
		rep(i,h)rep(j,w)c[j][i]=a[i][j];
		swap(h,w);
		swap(a,c);
		rep(i,h){
			unordered_set<int>ust;
			rep(j,w){
				if(a[i][j]){
					if(ust.count(a[i][j])){
						a[i][j]=0;
						continue;
					}
					ust.emplace(a[i][j]);
					++ans;
					a[i][j]=0;
				}
			}
			rep(j,w){
				if(ust.count(a[i][j]))a[i][j]=0;
			}
		}
	}

	swap(a,b);
	ll res=ans;
	ans=0;
	rep(i,h){
		unordered_set<int>ust;
		rep(j,w){
			if(a[i][j]){
				if(ust.count(a[i][j])){
					a[i][j]=0;
					continue;
				}
				bool ok=false;
				rep(k,h){
					if(k==i)continue;
					if(a[k][j]==a[i][j]){
						ok=true;
						break;
					}
				}
				if(!ok){
					ust.emplace(a[i][j]);
					a[i][j]=0;
					++ans;
				}
			}
		}
		rep(j,w){
			if(ust.count(a[i][j]))a[i][j]=0;
		}
	}
	vector<vector<int>>c(w,vector<int>(h));
	rep(i,h)rep(j,w)c[j][i]=a[i][j];
	swap(h,w);
	swap(a,c);
	rep(i,h){
		unordered_set<int>ust;
		rep(j,w){
			if(a[i][j]){
				if(ust.count(a[i][j])){
					a[i][j]=0;
					continue;
				}
				ust.emplace(a[i][j]);
				++ans;
				a[i][j]=0;
			}
		}
		rep(j,w){
			if(ust.count(a[i][j]))a[i][j]=0;
		}
	}
	chmin(res,ans);
	cout<<res<<"\n";
	rep(i,h)rep(j,w)if(a[i][j])assert(false);
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}