import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;

public class SubString
{

    final static int bufferSize = 1024 * 64;
    static byte[] buffer = new byte[bufferSize];

    public static String readLine(InputStream stream) throws IOException
    {
        StringBuilder sb = new StringBuilder();
        while (true)
        {
            stream.mark(bufferSize);
            int readBytes = stream.read(buffer, 0, bufferSize);
            for (int i = 0; i < readBytes - 1; ++i)
            {
                if (buffer[i] == '\n')
                {
                    stream.reset();
                    readBytes = stream.read(buffer, 0, i + 1) - 1;
                    break;
                }
            }
            if (readBytes > 0 && buffer[readBytes - 1] == '\n')
                readBytes--;
            for (int i = 0; i < readBytes; ++i)
                sb.append((char) buffer[i]);
            if (readBytes < bufferSize)
                break;
        }
        return sb.toString();
    }

    public static int getNum(String t)
    {
        int num = 0;
        int k = t.length();
        int reminder;
        int baghimande = 0;
        for (int j = 0; j < k; j++)
        {
            int n = t.charAt(j) - 'a' + 1;
            if (baghimande != 0)
                baghimande = (27 * baghimande) % 200009;
            else
                baghimande = 1;
            num = (num + n * baghimande) % 200009;
        }
        return num;
    }

    public static int getNum2(String t)
    {
        int num = 0;
        int k = t.length();
        int reminder;
        int baghimande = 0;
        for (int j = 0; j < k; j++)
        {
            int n = t.charAt(j) - 'a' + 1;
            if (baghimande != 0)
                baghimande = (27 * baghimande) % 100003;
            else
                baghimande = 1;
            num = (num + n * baghimande) % 100003;
        }
        return num;
    }

    public static void main(String[] args)
    {
        BufferedInputStream stream = new BufferedInputStream(System.in);
        try
        {
            String s = readLine(stream);
            String line2 = readLine(stream);
            int k = Integer.parseInt(line2);
            int l = s.length();
            int h = l - k + 1;
            boolean flag = false;
            int a = -1;
            int[] heapTable = new int[300012];
            int temp;
            int min = -1;
            for (int i = 0; i < h; i++)
            {
                String t = s.substring(i, i + k);
                temp = getNum(t) + getNum2(t);
                if (heapTable[temp] != 0)
                {
                    flag = true;
                    if (min == -1 || min > (heapTable[temp] - 1))
                        min = heapTable[temp] - 1;
                } else
                    heapTable[temp] = i + 1;
            }
            if (flag)
                System.out.println(min);
            else
                System.out.println("No Solution");
        } catch (IOException e)
        {
            e.printStackTrace();
        }
    }

}