#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1e6;
bool onPathTM[MAX_N + 1];
int parent[MAX_N + 1];
int dp[MAX_N + 1];
vector<int> adj[MAX_N + 1];
void dfs(int u, int p) {
parent[u] = p;
for (int v: adj[u]) {
if (v == p)
continue;
dfs(v, u);
}
}
void calcDp(int u, int p) {
int max1 = 0, max2 = 0;
int sons = 0;
for (int v: adj[u]) {
if (v == p)
continue;
calcDp(v, u);
if (!onPathTM[v]) {
if (dp[v] > max1) {
max2 = max1;
max1 = dp[v];
} else if (dp[v] > max2)
max2 = dp[v];
sons++;
}
}
dp[u] = (sons > 0) + max2 + (sons > 1) + max(0, sons - 2);
printf("%d %d\n", u, dp[u]);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, t, m;
cin >> n >> t >> m;
for (int e = 0; e < n - 1; e++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
dfs(t, 0);
int w = m;
while (w != t) {
onPathTM[w] = true;
w = parent[w];
}
calcDp(t, 0);
cout << dp[m] << "\n";
return 0;
}
