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

using ll = long long;
using ull = unsigned long long;

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

struct pair_hash {
	std::size_t operator()(const std::pair<int,int>& p) const { 
		return std::hash<int>()(p.first) ^ (std::hash<int>()(p.second) << 3);
	}
};

int n;
vector<S> g;

//unordered_map<pair<int,int>, ull, pair_hash> m;
constexpr int K = 900;
array<array<ull, K>, 100000> m;
// Hash node u up to distance d.
ull calc(int u, int d){
	if(d == 0) return g[u].v;
	auto&x = m[u][d];
	if(x > 0) return x-1;
	auto v = calc(g[u].l, d-1) + 13245*calc(g[u].r, d-1);// + 91841 * g[u].v;
	x = v+1;
	return v;
}

int main() {
	auto start = chrono::high_resolution_clock::now();

	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 I = 0;
	//m.reserve(2e7);
	for(auto &x : m) x.fill(0);
	for(int d = 0; d<K; ++d){
		auto now = chrono::high_resolution_clock::now();
		if(chrono::duration<double,ratio<1>>(now-start).count() > 1.0)
			break;

		auto ha = calc(a,d);
		auto hb = calc(b,d);
		if(ha != hb){
			cout << d << endl;
			return 0;
		}
	}


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