main.cpp

#include <deque>
#include <iostream>
#include <vector>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m, start;
    if (!(cin >> n >> m >> start)) {
        return 0;
    }
    vector<vector<int>> graph(n + 1);
    for (int i = 0; i < m; ++i) {
        int u, v;
        cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    vector<int> days(n + 1, -1);
    deque<int> q;
    days[start] = 0;
    q.push_back(start);
    while (!q.empty()) {
        int node = q.front();
        q.pop_front();
        for (int nxt : graph[node]) {
            if (days[nxt] != -1) {
                continue;
            }
            days[nxt] = days[node] + 1;
            q.push_back(nxt);
        }
    }
    int total_days = 0;
    int unreached = 0;
    for (int i = 1; i <= n; ++i) {
        if (days[i] == -1) {
            ++unreached;
        } else if (days[i] > total_days) {
            total_days = days[i];
        }
    }
    cout << "total_days=" << total_days << "\n";
    cout << "days=";
    for (int i = 1; i <= n; ++i) {
        if (i > 1) {
            cout << ' ';
        }
        cout << days[i];
    }
    cout << "\n";
    cout << "unreached=" << unreached << "\n";
    return 0;
}