#include <iostream>
#include <cstring>

using namespace std;
/*ifstream cin("input.txt");
ofstream cout("output.txt");*/
int n,m,i,j;
int qw[52][52];
int er[52][52];
char a[101];

struct vlad{
int come,l,c;
}b[2505];

int tryy(int l,int c)
{
    int s=0,i=0,come=0;
    b[++s].come=0;
    b[s].l=l;
    b[s].c=c;
    while(i<s)
    {
        i++;
        come=b[i].come;
        l=b[i].l;
        c=b[i].c;
        er[l][c]=1;
        if(come!=1 && qw[l][c]==qw[l-1][c] && er[l-1][c]==0)
        {
            b[++s].come=3;
            b[s].l=l-1;
            b[s].c=c;
            er[l-1][c]=1;

        }
        if(come!=2 && qw[l][c]==qw[l][c+1] && er[l][c+1]==0)
        {
            b[++s].come=4;
            b[s].l=l;
            b[s].c=c+1;
            er[l][c+1]=1;

        }
        if(come!=3 && qw[l][c]==qw[l+1][c] &&   er[l+1][c]==0)
        {
            b[++s].come=1;
            b[s].l=l+1;
            b[s].c=c;
            er[l+1][c]=1;

        }
        if(come!=4 && qw[l][c]==qw[l][c-1] && er[l][c-1]==0)
        {
            b[++s].come=2;
            b[s].l=l;
            b[s].c=c-1;
            er[l][c-1]=1;

        }
    }
    return i;
}


int main()
{
    int cer=0,qww=0,maxx=0;
    cin>>cer>>n>>m; cin.get();
    for(i=1;i<=n;i++)
    {
        cin.getline(a,100);
        for(j=0;j<m;j++)
            qw[i][j+1]=a[j]-'A'+1;
    }
    if(cer==1)
    {
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=m;j++)
                if(er[i][j]==0)
                {
                    qww=tryy(i,j);
                    if(qww>maxx)
                    {
                        maxx=qww;
                    }
                }
        }

     cout<<maxx;
     }
    return 0;
}