#include<bits/stdc++.h>
using namespace std;


#define li          long long int
#define uli         unsigned long long int
#define rep(i,to)   for(li i=0;i<((li)(to));i++)
#define repp(i,start,to)    for(li i=(li)(start);i<((li)(to));i++)
#define pb          push_back
#define sz(v)       ((li)(v).size())
#define bgn(v)      ((v).begin())
#define eend(v)     ((v).end())
#define allof(v)    (v).begin(), (v).end()
#define dodp(v,n)       memset(v,(li)n,sizeof(v))
#define bit(n)      (1ll<<(li)(n))
#define mp(a,b)     make_pair(a,b)
#define rin rep(i,n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1


#define idp if(DBGP)
#define F first
#define S second
#define p2(a,b)     idp cout<<a<<"\t"<<b<<endl
#define p3(a,b,c)       idp cout<<a<<"\t"<<b<<"\t"<<c<<endl
#define p4(a,b,c,d)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<endl
#define p5(a,b,c,d,e)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<endl
#define p6(a,b,c,d,e,f)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<endl
#define p7(a,b,c,d,e,f,g)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<endl
#define p8(a,b,c,d,e,f,g,h)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<endl
#define p9(a,b,c,d,e,f,g,h,i)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<"\t"<<i<<endl
#define p10(a,b,c,d,e,f,g,h,i,j)        idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<"\t"<<i<<"\t"<<j<<endl
#define foreach(it,v)   for(__typeof((v).begin()) it=(v).begin(); it!=(v).end(); ++it)
#define p2p(x)      idp p2((x).F, (x).S)
#define dump(x,n)   idp{rep(i,n){cout<<x[i]<<" ";}puts("");}
#define dump2(x,n)  idp{rep(i,n){cout<<"["<<x[i].F<<" , "<<x[i].S<<"] ";}puts("");}
#define dumpi(x)    idp{foreach(it, x){cout<<(*it)<<" ";}puts("");}
#define dumpi2(x)   idp{foreach(it, x){cout<<"["<<(it)->F<<" , "<<(it)->S<<"] ";}puts("");}

#define read2d(a,w,h)   rep(i,h)rep(j,w)cin>>a[i][j]
#define dump2d(a,w,h)   rep(i,h){rep(j,w)cout<<a[i][j]<<" ";puts("");}

typedef pair<li, li> PI;

li n, m;
li a[333][333];

inline void process(deque<li>& dq, set<li>& banned) {
    while (!dq.empty()) {
        if (banned.count(dq.front()) > 0) {
            dq.pop_front();
        } else {
            return;
        }
    }
}


inline bool check(li x) {
    vector<deque<li>> qs(n);
    rin{
        rep(j, m) {
            qs[i].pb(a[i][j]);
        }
    }
    set<li> banned;
    while (true) {
        map<li, li> cnt;
        rin{
            process(qs[i], banned);
            if (qs[i].empty()) {
                return false;
            }
            cnt[qs[i].front()]++;
        }
        bool ok = true;
        for (auto& kv : cnt) {
            if (kv.S > x) {
                banned.insert(kv.F);
                ok = false;
            }
        }
        if (ok) {
            return true;
        }
    }
    return false;
}

int main() {
    cin >> n >> m;
    rin{
        rep(j, m) {
            cin >> a[i][j];
            a[i][j]--;
        }
    }
    li l = 0;
    li r = n;
    while (l + 1 < r) {
        li med = (l + r) / 2;
        if (check(med)) {
            r = med;
        } else {
            l = med;
        }
    }
    cout << r << endl;

    return 0;
}

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
using namespace std;
int n,m,h[2010][2010],l[2010][2010],r[2010][2010],ans;
char s[2010][2010];
int main()
{
	scanf("%d %d",&n,&m);getchar();
	ans=max(n,m);
	for(int i=1;i<=n;i++) scanf("%s",s[i]+1);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
		{
			if(j==1||i==1) h[i][j]=1;
			else h[i][j]=((s[i][j]==s[i][j-1])==(s[i-1][j]==s[i-1][j-1]))?h[i-1][j]:i;
		}
	for(int i=1;i<=n;i++)
	{
		if(i==1) for(int j=1;j<=m;j++) l[i][j]=1,r[i][j]=m;
		else
		{
			l[i][1]=1;for(int j=2  ;j<=m;j++) l[i][j]=(s[i][j]==s[i-1][j])==(s[i][j-1]==s[i-1][j-1])?l[i][j-1]:j;
			r[i][m]=m;for(int j=m-1;j>=1;j--) r[i][j]=(s[i][j]==s[i-1][j])==(s[i][j+1]==s[i-1][j+1])?r[i][j+1]:j;
		}
		for(int j=1;j<=m;j++)
		{
			if(h[i][j]==i) l[i][j]=1,r[i][j]=m;
			else l[i][j]=max(l[i][j],l[i-1][j]),r[i][j]=min(r[i][j],r[i-1][j]);
			int N=i-h[i][j]+1,M=r[i][j]-l[i][j]+1;
			ans=max(ans,N*M);
		}
	}
	printf("%d",ans);
}