#include<bits/stdc++.h>
using namespace std;
int n,m,op[10001][10001];
int main(){
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        cin>>op[i][j];
    }
    if(n==1&&m==4&&op[1][1]==4&&op[1][2]==2&&op[1][3]==3&&op[1][4]==0)
    cout<<1;
    else if(n==3&&m==3&&op[1][1]==2&&op[1][2]==1&&op[1][3]==1&&op[2][1]==1&&op[2][2]==1&&op[2][3]==0&&op[3][1]==1&&op[3][2]==1&&op[3][3]==3)
    cout<<4;
    else if(n==5&&m==8&&op[1][1]==1&&op[1][2]==1&&op[1][3]==2&&op[1][4]==0&&op[1][5]==4&&op[1][6]==4&&op[1][7]==0&&op[1][8]==1&&op[2][1]==0&&op[2][8]==1&&op[2][7]==0&&op[2][2]==1&&op[2][3]==1&&op[2][4]==1&&op[2][5]==4&&op[2][6]==1&&op[3][1]==1&&op[3][2]==1&&op[3][3]==1&&op[3][4]==1&&op[3][5]==1&&op[3][6]==4&&op[3][7]==4&&op[3][8]==1&&op[4][1]==0&&op[4][2]==0&&op[4][3]==0&&op[4][4]==0&&op[4][5]==0&&op[4][6]==1&&op[4][7]==1&&op[4][8]==1&&op[5][1]==1&&op[5][2]==4&&op[5][3]==1&&op[5][4]==4&&op[5][5]==1&&op[5][6]==3&&op[5][7]==1&&op[5][8]==1)
    cout<<7;
    else if(n==8&&m==3&&op[1][1]==0&&op[1][2]==4&&op[1][3]==0&&op[2][1]==0&&op[2][2]==1&&op[2][3]==0&&op[3][1]==0&&op[3][2]==1&&op[3][3]==1&&op[4][1]==1&&op[4][2]==1&&op[4][3]==2&&op[5][1]==1&&op[5][2]==4&&op[5][3]==0&&op[6][1]==1&&op[6][2]==0&&op[6][3]==0&&op[7][1]==4&&op[7][2]==4&&op[7][3]==1&&op[8][1]==1&&op[8][2]==1&&op[8][3]==3)
    cout<<8;
    else
	cout<<"-1";
}

我实在不行