import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.List;
import java.util.Scanner;
import java.util.Vector;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
*/public class Main {
	public static void main(String[] args) throws IOException {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		
		Reader in = new Reader();
		//Scanner in = new Scanner(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		DCompression solver = new DCompression();
		solver.solve(1, in, out);
		out.close();
	}
static class DCompression   {
public void solve(int testNumber, Reader in, PrintWriter out) throws IOException {

        int n = in.nextInt();
        char[][] matrix = new char[n][];

        in.readLine();
        for(int i = 0; i < n; i++){
            matrix[i] = in.readLine().toCharArray();
        }

        List<Integer> divisores = new Vector<>();

        for(int i = n; i >= 2; i--){
            if(n % i == 0) divisores.add(i);
        }

        for(Integer div: divisores){
            if(isOk(matrix, div, n, out)){
                out.println(div);
                return;
            }
        }

        out.println(1);
    }

private boolean isOk(char[][] matrix, int x, int n, PrintWriter out) {

        int m = n / x;

        for(int i = 0; i < m; i++){

            for(int j = 0; j < m; j++){

                int offsetRow = i * x;
                int offsetCol = j * x;

//                out.println("-----------------------------------------------");
//                out.println("(" + i + ", " + j + ") " + x);

                boolean ant = getValor(matrix[offsetRow][offsetCol / 4], offsetCol % 4, out);

                for(int ki = offsetRow; ki < offsetRow + x; ki++){

                    for(int kj = offsetCol; kj < offsetCol + x; kj++){

                        boolean pos = getValor(matrix[ki][kj / 4], kj % 4, out);
//                      out.print("(" + ki + ", " + kj + ") " + " -> " + pos);

                        if(pos != ant) return false;
                    }


//                    out.println();

                }

            }
        }

        return true;
    }

private boolean getValor(char v, int k, PrintWriter out) {

        int x = -1;

        if(v == 'F') x = 15;
        else if(v == 'E') x = 14;
        else if(v == 'D') x = 13;
        else if(v == 'C') x = 12;
        else if(v == 'B') x = 11;
        else if(v == 'A') x = 10;
        else x = v - '0';

 //       out.println(v + ", " + k + ", " + ((x >> k) % 2));

        return ((x >> k) % 2) == 1;
    }

}
}


class Reader 
{ 
    final private int BUFFER_SIZE = 1 << 16; 
    private DataInputStream din; 
    private byte[] buffer; 
    private int bufferPointer, bytesRead; 

    public Reader() 
    { 
        din = new DataInputStream(System.in); 
        buffer = new byte[BUFFER_SIZE]; 
        bufferPointer = bytesRead = 0; 
    } 

    public Reader(String file_name) throws IOException 
    { 
        din = new DataInputStream(new FileInputStream(file_name)); 
        buffer = new byte[BUFFER_SIZE]; 
        bufferPointer = bytesRead = 0; 
    } 

    public String readLine() throws IOException 
    { 
        byte[] buf = new byte[5500]; // line length 
        int cnt = 0, c; 
        while ((c = read()) != -1) 
        { 
            if (c == '\n') 
                break; 
            buf[cnt++] = (byte) c; 
        } 
        return new String(buf, 0, cnt); 
    } 

    public int nextInt() throws IOException 
    { 
        int ret = 0; 
        byte c = read(); 
        while (c <= ' ') 
            c = read(); 
        boolean neg = (c == '-'); 
        if (neg) 
            c = read(); 
        do
        { 
            ret = ret * 10 + c - '0'; 
        }  while ((c = read()) >= '0' && c <= '9'); 

        if (neg) 
            return -ret; 
        return ret; 
    } 

    public long nextLong() throws IOException 
    { 
        long ret = 0; 
        byte c = read(); 
        while (c <= ' ') 
            c = read(); 
        boolean neg = (c == '-'); 
        if (neg) 
            c = read(); 
        do { 
            ret = ret * 10 + c - '0'; 
        } 
        while ((c = read()) >= '0' && c <= '9'); 
        if (neg) 
            return -ret; 
        return ret; 
    } 

    public double nextDouble() throws IOException 
    { 
        double ret = 0, div = 1; 
        byte c = read(); 
        while (c <= ' ') 
            c = read(); 
        boolean neg = (c == '-'); 
        if (neg) 
            c = read(); 

        do { 
            ret = ret * 10 + c - '0'; 
        } 
        while ((c = read()) >= '0' && c <= '9'); 

        if (c == '.') 
        { 
            while ((c = read()) >= '0' && c <= '9') 
            { 
                ret += (c - '0') / (div *= 10); 
            } 
        } 

        if (neg) 
            return -ret; 
        return ret; 
    } 

    private void fillBuffer() throws IOException 
    { 
        bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE); 
        if (bytesRead == -1) 
            buffer[0] = -1; 
    } 

    private byte read() throws IOException 
    { 
        if (bufferPointer == bytesRead) 
            fillBuffer(); 
        return buffer[bufferPointer++]; 
    } 

    public void close() throws IOException 
    { 
        if (din == null) 
            return; 
        din.close(); 
    } 
}