#define _USE_MATH_DEFINES
#include <string>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <fstream>
#include <deque>
#include <vector>
#include <stdlib.h>
#include <set>
#include <iostream>
#include <cctype>
#include <climits>
#include <queue>

using namespace std;

int main() {

    ifstream in("input.txt");
    ofstream out("output.txt");

    int n, vStart, vFinish;
    int mas[101][101], used[101];
    in >> n;
    for (int i = 0; i < n; i++) {
        used[i] = -1;
        for (int j = 0; j < n; j++) {
            in >> mas[i][j];
        }
    }

    queue <int> q;
    in >> vStart >> vFinish;
    q.push(--vStart);
    used[vStart] = 0;

    while (!q.empty()) {
        int u = q.front();
        q.pop();
        for (int j = 0; j < n; j++) {
            if (mas[u][j] == 1 && used[j] == -1) {
                used[j] = used[u] + 1;
                q.push(j);
            }
        }
    }

    out << used[--vFinish];

    in.close();
    out.close();
    return 0;
}