#include <iostream>
#include <vector>

using namespace std;

vector<int> G[100];

int n, start, max_v, max_dist = -1;
bool color[100];

void dfs(int v, int dist)
{
    color[v] = true;
    for (int i = 0; i < G[v].size(); ++i)
    {
        if (!color[G[v][i]])
        {
            dfs(G[v][i], dist + 1);
        }
        if (dist > max_dist)
        {
            max_dist = dist;
            max_v = v;
        }
    }
}

int main()
{
    cin >> n >> start;
    --start;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            int c;
            cin >> c;
            if (c==1)
            {
                G[i].push_back(j);
            }
        }
    }
    dfs(start, 0);
    cout << max_v+1;
}