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

struct S {
	int l, r, v;
};
struct T {
	int a, b;
};

int n;
vector<S> g;

int get_dist(int a, bool want){
	vector<bool> done(n, false);
	queue<pair<int,int>> q;
	q.push({a,0});
	while(!q.empty()){
		int u = q.front().first, d = q.front().second;
		q.pop();
		if(done[u]) continue;
		done[u] = true;
		if(g[u].v == want){
			return d;
		}
		q.push({g[u].l, d+1});
		q.push({g[u].r, d+1});
	}
	return n+10;
}

int main() {
	int a, b;
	cin >> n >> a >> b;
	g.resize(n);
	for(auto &x : g) cin >> x.l >> x.r >> x.v;

	if(g[a].v != g[b].v){
		cout << 0 << endl;
		return 0;
	}

	int adist = get_dist(a, !g[a].v);
	int bdist = get_dist(b, !g[b].v);
	cerr << adist << ' ' << bdist << endl;
	if(adist != bdist){
		cout << min(adist, bdist) << endl;
		return 0;
	}

	cout << "INDISTINGUISHABLE" << endl;
	return 0;
}