#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int H,W;
int A[505][505];

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>H>>W;
	FOR(y,H) FOR(x,W) cin>>A[y][x];
	
	int ret=0;
	while(1) {
		int ma=0,tar=0,num=0;;
		FOR(y,H) {
			
			map<int,int> R;
			FOR(x,W) if(A[y][x]) {
				R[A[y][x]]++;
				if(R[A[y][x]]>ma) {
					ma=R[A[y][x]];
					tar=y;
					num=A[y][x];
				}
			}
		}
		FOR(x,W) {
			map<int,int> R;
			FOR(y,H) if(A[y][x]) {
				R[A[y][x]]++;
				if(R[A[y][x]]>ma) {
					ma=R[A[y][x]];
					tar=H+x;
					num=A[y][x];
				}
			}
		}
		if(ma==0) break;
		ret++;
		if(tar<H) {
			FOR(x,W) if(A[tar][x]==num) A[tar][x]=0;
		}
		else {
			FOR(y,H) if(A[y][tar-H]==num) A[y][tar-H]=0;
		}
		
	}
	cout<<ret<<endl;
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}