#line 1 "a.cpp"
#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
#line 1 "/home/kotatsugame/library/graph/MF_Dinic.cpp"
//Dinic O(EV^2)
#line 3 "/home/kotatsugame/library/graph/MF_Dinic.cpp"
#include<utility>
#line 5 "/home/kotatsugame/library/graph/MF_Dinic.cpp"
#include<queue>
#include<limits>
template<typename T>
struct MF{
	struct edge{
		int to,rev;
		T cap;
	};
	vector<vector<edge> >G;
	vector<int>level,iter;
	MF(int n_=0):G(n_),level(n_),iter(n_){}
	void add_edge(int from,int to,T cap)
	{
		G[from].push_back({to,(int)G[to].size(),cap});
		G[to].push_back({from,(int)G[from].size()-1,0});
	}
	T dfs(int u,int t,T f)
	{
		if(u==t)return f;
		for(;iter[u]<G[u].size();iter[u]++)
		{
			edge&e=G[u][iter[u]];
			if(e.cap>0&&level[u]<level[e.to])
			{
				T d=dfs(e.to,t,min(f,e.cap));
				if(d>0)
				{
					e.cap-=d;
					G[e.to][e.rev].cap+=d;
					return d;
				}
			}
		}
		return 0;
	}
	T max_flow(int s,int t)
	{
		T ret=0;
		for(;;)
		{
			fill(level.begin(),level.end(),-1);
			queue<int>P;
			level[s]=0;
			P.push(s);
			while(!P.empty())
			{
				int u=P.front();P.pop();
				for(edge&e:G[u])
				{
					if(e.cap>0&&level[e.to]<0)
					{
						level[e.to]=level[u]+1;
						P.push(e.to);
					}
				}
			}
			if(level[t]<0)return ret;
			fill(iter.begin(),iter.end(),0);
			for(T f;(f=dfs(s,t,numeric_limits<T>::max()))>0;)ret+=f;
		}
	}
};
#line 6 "a.cpp"
int N,M;
main()
{
	cin>>N>>M;
	vector<pair<int,pair<int,int> > >A(N*M);
	for(int i=0;i<N;i++)for(int j=0;j<M;j++)
	{
		cin>>A[i*M+j].first;
		A[i*M+j].second=make_pair(i,j);
	}
	sort(A.begin(),A.end());
	int ans=0;
	for(int i=0;i<A.size();)
	{
		if(A[i].first==0)
		{
			i++;
			continue;
		}
		int j=i;
		MF<int>P(N+M+2);
		while(j<A.size()&&A[i].first==A[j].first)
		{
			P.add_edge(A[j].second.first,A[j].second.second+N,1);
			j++;
		}
		for(int k=0;k<N;k++)P.add_edge(N+M,k,1);
		for(int k=0;k<M;k++)P.add_edge(k+N,N+M+1,1);
		i=j;
		ans+=P.max_flow(N+M,N+M+1);
	}
	cout<<ans<<endl;
}