#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream fin("bfs.in");
ofstream fout("bfs.out");

int visit[100001];
vector<int> a[100001]; //adiacenta
queue<int> q;
int n, m, s, x, y;

void bfs(int s)
{
    int i, top;
    for (i = 1; i <= n; i++)
        //visit[i]=false;
        visit[i] = -1;
    q.push(s);
    //visit[s] = true;
    visit[s] = 0;
    //vector<int> :: iterator it;
    while (!q.empty())
    {
        top = q.front();
        q.pop();
        for (i = 0; i < a[top].size(); i++)
        {
            if (visit[a[top][i]] == -1)
            {
                visit[a[top][i]] = visit[top] + 1;
                q.push(a[top][i]);
            }
        }
    }
}

int main()
{

    fin >> n >> m >> s;
    for (int i = 1; i <= m; i++)
    {
        fin >> x >> y;
        a[x].push_back(y);
    }
    bfs(s);

    // for(int i = 1; i <= n; i++)
    //     fout << visit[i] << ' ';
    fout << visit[a[2][3]];

    return 0;
}