import java.io.PrintStream;
import java.util.Scanner;

public class Main{
   public static void main(String[] args) throws Exception {
       Scanner in = new Scanner(System.in);
       PrintStream out = new PrintStream(System.out);
       int n = in.nextInt(), s = in.nextInt() - 1, f = in.nextInt() - 1, h = 0, t = 0, now;
       int[][] g = new int[n][n];
       int[] q = new int[n - 1], distance = new int[n];
       boolean[] used = new boolean[n];

       for(int i = 0; i < n; i++) {
           for(int j = 0; j< n; j++) {
               g[i][j] = in.nextInt();
           }
       }

       q[t++ % q.length] = s;
       used[s] = true;
       while(h !=  t) {
           now = q[h++ % q.length];
           for(int i = 0; i < n; i++) {
               if(g[now][i] == 1 && !used[i]) {
                   q[t++ % q.length] = i;
                   used[i] = true;
                   distance[i] = distance[now] + 1;
               }
           }
       }
       out.println(distance[f]);
       out.flush();
   }
}