Polycarpus has n friends in Tarasov city. Polycarpus knows phone numbers of all his friends: they are strings s1, s2, ..., sn. All these strings consist only of digits and have the same length. 

Once Polycarpus needed to figure out Tarasov city phone code. He assumed that the phone code of the city is the longest common prefix of all phone numbers of his friends. In other words, it is the longest string c which is a prefix (the beginning) of each si for all i (1 ≤ i ≤ n). Help Polycarpus determine the length of the city phone code. 

Input

The first line of the input contains an integer n (2 ≤ n ≤ 3·104) — the number of Polycarpus's friends. The following n lines contain strings s1, s2, ..., sn — the phone numbers of Polycarpus's friends. It is guaranteed that all strings consist only of digits and have the same length from 1 to 20, inclusive. It is also guaranteed that all strings are different.

Output

Print the number of digits in the city phone code.

Examples

Input

4
00209
00219
00999
00909


Output

2


Input

2
1
2


Output

0


Input

3
77012345678999999999
77012345678901234567
77012345678998765432


Output

12

Note

A prefix of string t is a string that is obtained by deleting zero or more digits from the end of string t. For example, string "00209" has 6 prefixes: "" (an empty prefix), "0", "00", "002", "0020", "00209".

In the first sample the city phone code is string "00".

In the second sample the city phone code is an empty string.

In the third sample the city phone code is string "770123456789".
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;

/**
 * @author Ivan Pryvalov (ivan.pryvalov@gmail.com)
 */
public class KROK_Q_A implements Runnable{
	
	private void solve() throws IOException {
		int n = scanner.nextInt();
		String[] s = new String[n];
		for (int i = 0; i < n; i++) {
			s[i] = scanner.nextToken();						
		}
		
		int pos = 0;
		while(pass(s,pos)){
			pos++;
		}
		out.println(pos);
	}

	private boolean pass(String[] s, int pos) {
		char common = s[0].charAt(pos);
		for (int i = 1; i < s.length; i++) {
			if (s[i].charAt(pos)!=common)
				return false;
		}
		return true;
	}

	/////////////////////////////////////////////////
	final int BUF_SIZE = 1024 * 1024 * 8;//important to read long-string tokens properly
	final int INPUT_BUFFER_SIZE = 1024 * 1024 * 8 ;
	final int BUF_SIZE_INPUT = 1024;
	
	final int BUF_SIZE_OUT = 1024;
	
	boolean inputFromFile = false;
	String filenamePrefix = "A-small-attempt0";
	String inSuffix = ".in";
	String outSuffix = ".out";
	
	//InputStream bis;
	//OutputStream bos;
	PrintStream out;
	ByteScanner scanner;
	ByteWriter writer;
	
	@Override
	public void run() {
		try{
			InputStream bis = null;
			OutputStream bos = null;
			//PrintStream out = null;
			if (inputFromFile){
				File baseFile = new File(getClass().getResource("/").getFile());
				bis = new BufferedInputStream(
						new FileInputStream(new File(
								baseFile, filenamePrefix+inSuffix)),
								INPUT_BUFFER_SIZE);
				bos = new BufferedOutputStream(
						new FileOutputStream(
								new File(baseFile, filenamePrefix+outSuffix)));
				out = new PrintStream(bos);
			}else{
				bis = new BufferedInputStream(System.in, INPUT_BUFFER_SIZE);
				bos = new BufferedOutputStream(System.out);
				out = new PrintStream(bos);
			}
			scanner = new ByteScanner(bis, BUF_SIZE_INPUT, BUF_SIZE);
			writer = new ByteWriter(bos, BUF_SIZE_OUT);
			
			solve();
			out.flush();
		}catch (Exception e) {
			e.printStackTrace();
			System.exit(1);
		}
	}
	
	public interface Constants{
		final static byte ZERO = '0';//48 or 0x30
		final static byte NINE = '9';
		final static byte SPACEBAR = ' '; //32 or 0x20
		final static byte MINUS = '-'; //45 or 0x2d	
		
		final static char FLOAT_POINT = '.';
	}
	
	public static class EofException extends IOException{
	}
	
	public static class ByteWriter implements Constants {
		
		int bufSize = 1024;
		byte[] byteBuf = new byte[bufSize];
		OutputStream os;
		
		public ByteWriter(OutputStream os, int bufSize){
			this.os = os;
			this.bufSize = bufSize;
		}
		
		public void writeInt(int num) throws IOException{
	         int byteWriteOffset = byteBuf.length;
	         if (num==0){
	        	 byteBuf[--byteWriteOffset] = ZERO;
	         }else{
	        	 int numAbs = Math.abs(num);
	        	 while (numAbs>0){
	        		 byteBuf[--byteWriteOffset] = (byte)((numAbs % 10) + ZERO);
	        		 numAbs /= 10;
	        	 }
	        	 if (num<0)
	        		 byteBuf[--byteWriteOffset] = MINUS;
	         }
	         os.write(byteBuf, byteWriteOffset, byteBuf.length - byteWriteOffset);
		}
		
		/**
		 * Please ensure ar.length <= byteBuf.length!
		 * 
		 * @param ar
		 * @throws IOException
		 */
		public void writeByteAr(byte[] ar) throws IOException{
			for (int i = 0; i < ar.length; i++) {
				byteBuf[i] = ar[i];
			}
			os.write(byteBuf,0,ar.length);
		}
		
		public void writeSpaceBar() throws IOException{
			byteBuf[0] = SPACEBAR;
			os.write(byteBuf,0,1);
		}
		
	}
	
	public static class ByteScanner implements Constants{
		
		InputStream is;
		
		public ByteScanner(InputStream is, int bufSizeInput, int bufSize){
			this.is = is;
			this.bufSizeInput = bufSizeInput;
			this.bufSize = bufSize;
			
			byteBufInput = new byte[this.bufSizeInput];
			byteBuf = new byte[this.bufSize];
		}
		
		public ByteScanner(byte[] data){
			byteBufInput = data;
			bufSizeInput = data.length;
			bufSize = data.length;
			byteBuf = new byte[bufSize];
			byteRead = data.length;
			bytePos = 0;
		}
		
		private int bufSizeInput;
		private int bufSize;
		
		byte[] byteBufInput;
		byte by=-1;
		int byteRead=-1;
		int bytePos=-1;

		byte[] byteBuf;
		int totalBytes;
		
		boolean eofMet = false;
		
		private byte nextByte() throws IOException{
			
			if (bytePos<0 || bytePos>=byteRead){
				byteRead = is==null? -1: is.read(byteBufInput);
				bytePos=0;
				if (byteRead<0){
					byteBufInput[bytePos]=-1;//!!!
					if (eofMet)
						throw new EofException();
					eofMet = true;
				}
			}
			return byteBufInput[bytePos++];
		}
		
		/**
		 * Returns next meaningful character as a byte.<br>
		 * 
		 * @return
		 * @throws IOException
		 */
		public byte nextChar() throws IOException{
			while ((by=nextByte())<=0x20);
			return by;
		}
		
		/**
		 * Returns next meaningful character OR space as a byte.<br>
		 * 
		 * @return
		 * @throws IOException
		 */
		public byte nextCharOrSpacebar() throws IOException{
			while ((by=nextByte())<0x20);
			return by;
		}
		
	    /**
	     * Reads line.
	     * 
	     * @return
	     * @throws IOException
	     */
	    public String nextLine() throws IOException {
            readToken((byte)0x20);
            return new String(byteBuf,0,totalBytes);
	    }
	    
	    public byte[] nextLineAsArray() throws IOException {
            readToken((byte)0x20);
            byte[] out = new byte[totalBytes];
            System.arraycopy(byteBuf, 0, out, 0, totalBytes);
            return out;
	    }
	    
		
	    /**
	     * Reads token. Spacebar is separator char.
	     * 
	     * @return
	     * @throws IOException
	     */
	    public String nextToken() throws IOException {
            readToken((byte)0x21);
            return new String(byteBuf,0,totalBytes);
	    }
	    
	    /**
	     * Spacebar is included as separator char
	     * 
	     * @throws IOException
	     */
	    private void readToken() throws IOException {	    	
            readToken((byte)0x21);
	    }
	    
	    private void readToken(byte acceptFrom) throws IOException {
            totalBytes = 0;
            while ((by=nextByte())<acceptFrom);
            byteBuf[totalBytes++] = by;
            while ((by=nextByte())>=acceptFrom){
                byteBuf[totalBytes++] = by;
            }
	    }
		
	    public int nextInt() throws IOException{
			readToken();
			int num=0, i=0;
			boolean sign=false;
			if (byteBuf[i]==MINUS){
				sign = true;
				i++;
			}
			for (; i<totalBytes; i++){
				num*=10;
				num+=byteBuf[i]-ZERO;
			}
			return sign?-num:num;
		}
		
		public long nextLong() throws IOException{
			readToken();
			long num=0;
			int i=0;
			boolean sign=false;
			if (byteBuf[i]==MINUS){
				sign = true;
				i++;
			}
			for (; i<totalBytes; i++){
				num*=10;
				num+=byteBuf[i]-ZERO;
			}
			return sign?-num:num;
		}
		
		/*
		//TODO test Unix/Windows formats
		public void toNextLine() throws IOException{
			while ((ch=nextChar())!='\n');
		}
		*/
		
		public double nextDouble() throws IOException{
			readToken();
			char[] token = new char[totalBytes];
			for (int i = 0; i < totalBytes; i++) {
				token[i] = (char)byteBuf[i];
			}
			return Double.parseDouble(new String(token));
		}
	    
	}
	
	public static void main(String[] args) {
		new KROK_Q_A().run();
	}
	
}
