BFS

#include<bits/stdc++.h>

using namespace std;

const int INF = (int)1e9;

main()
{
    int n, m, ans = 0;
    cin >> n;
    vector<vector<int>> g(n + 1, vector<int> (n + 1));
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= n; j++)
            cin >> g[i][j];
    int start, finish;
    cin >> start >> finish;
    vector<int> p(n + 1, INF);
    p[start] = 0;
    queue<int> q;
    q.push(start);
    while(!q.empty())
    {
        int cur = q.front();
        q.pop();
        for(int i = 1; i <= n; i++)
            if(g[cur][i] && p[i] == INF)
            {
                p[i] = p[cur] + 1;
                q.push(i);
            }
    }
    if(p[finish] == INF)
        cout << -1;
    else
        cout << p[finish];
}