#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using vi = vector<ll>;
using vvi = vector<vi>;
using ii = pair<ll, ll>;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n, a, b;
	cin >> n >> a >> b;

	vi l(n), r(n), t(n);
	vvi pf(n);
	for (int i = 0; i < n; ++i)
		cin >> l[i] >> r[i] >> t[i],
		pf[l[i]].push_back(i),
		pf[r[i]].push_back(i);

	vvi dt(2, vi(n, -1LL));
	queue<ii> q;
	for (int i = 0; i < n; ++i)
		dt[t[i]][i] = 0,
		q.push({t[i], i});

	while (!q.empty()) {
		int c, i;
		tie(c, i) = q.front();
		q.pop();

		for (int j : pf[i])
			if (dt[c][j] < 0)
				dt[c][j] = dt[c][i] + 1,
				q.push({c, j});
	}

	int ans = -1;
	if (dt[0][a] != dt[1][b] && (ans < 0 || min(dt[0][a], dt[1][b]) < ans))
		ans = min(dt[0][a], dt[1][b]);
	if (dt[1][a] != dt[0][b] && (ans < 0 || min(dt[1][a], dt[0][b]) < ans))
		ans = min(dt[1][a], dt[0][b]);

	if (ans < 0)
		cout << "indistinguishable" << endl;
	else
		cout << ans << endl;

	return 0;
}