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

struct S {
	int l, r, v;
};
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>, ll, pair_hash> m;
ll 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) + calc(g[u].r, d-1);
	x = v+1;
	return v;
}

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

	// Return the lowest distance at which the number of 1s differs.
	auto start = chrono::high_resolution_clock::now();
	for(int d = 0; d <= n; ++d){
		auto now = chrono::high_resolution_clock::now();
		if(chrono::duration<double,ratio<1>>(now-start).count() > 1.5)
			break;

		if(calc(a, d) != calc(b, d)){
			cout << d << endl;
			return 0;
		}
	}
	
	cout << "INDISTINGUISHABLE" << endl;
	return 0;
}