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

#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define rep(i,a,b) for(auto i = (a); i != (b); ++i)
#define REP(i,n) rep(i,0,n)
#define all(v) (v).begin(), (v).end()

typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ii> vii;

struct UF {
	vi par, rnk;

	UF() : par(), rnk() {}
	UF(int n) : par(n, -1), rnk(n, 0) {}

	int find(int u) { return par[u] < 0 ? u : par[u] = find(par[u]); }
	bool merge(int u, int v) {
		if ((u = find(u)) == (v = find(v))) return false;
		if (rnk[u] > rnk[v]) swap(u, v);
		if (rnk[u] == rnk[v]) rnk[v]++;
		par[u] = v;
		return true;
	}
};

const int maxn = 1e6;
const int INF = 1e9;

int N, L[maxn], R[maxn];
bool T[maxn];
UF uf(maxn);

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	int a, b;
	cin >> N >> a >> b;
	REP(i, N) {
		int t;
		cin >> L[i] >> R[i] >> t;
		T[i] = t != 0;
	}

	queue<ii> q;
	q.emplace(a, b);

	ii marker(a, b);
	int ret = 0;

	ii lastAdded(a, b);
	while (!q.empty()) {
		ii cur = q.front();
		q.pop();

		if (uf.find(cur.x) == uf.find(cur.y)) {
			// assert(T[cur.x] == T[cur.y]);

			if (cur == marker) {
				marker = lastAdded;
				ret++;
			}
			continue;
		}

		if (T[cur.x] != T[cur.y]) {
			cout << ret << endl;
			return 0;
		}

		uf.merge(cur.x, cur.y);
		q.emplace(L[cur.x], L[cur.y]);
		q.push(lastAdded = ii(R[cur.x], R[cur.y]));

		// increase height.
		if (cur == marker) {
			marker = lastAdded;
			ret++;
		}
	}
	cout << "indistinguishable" << endl;
	return 0;
}