#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int
main()
{
  int n, m, a;
  while (cin >> n >> m >> a) {
    vector<pair<int, int> > v[n + 1];
    if (n == 0 and m == 0 and a == 0) { break; }
    for (int i = 0; i < m; i++) {
      int p, q, r;
      cin >> p >> q >> r;
      v[q].push_back(make_pair(p, r));
      v[r].push_back(make_pair(p, q));
    }
    for (int i = 1; i <=n; i++) {
      sort(v[i].begin(), v[i].end());
      reverse(v[i].begin(), v[i].end());
    }
    int k = a;
    if (v[k].size() == 0) {
      cout << a << endl;
      continue;
    }
    int now_h = v[k].begin()->first + 1;

    while (true) {
      bool flag = false;

      for (int i = 0; i < v[k].size(); i++) {
        if (v[k][i].first < now_h) {
          now_h = v[k][i].first;
          k = v[k][i].second;
          flag = true;
          break;
        }
      }
      if (!flag) {
        break;
      }
    }
    cout << k << endl;
  }
  return 0;
}