/* Problem URL: https://cses.fi/problemset/task/1684 */ #include #include #include using namespace std; using namespace __gnu_pbds; template > using ordered_set = tree; #define V vector #define rmin(a, b) a = min(a, b) #define rmax(a, b) a = max(a, b) #define rep(i, lim) for (int i = 0; i < (lim); i++) #define nrep(i, s, lim) for (int i = s; i < (lim); i++) #define repv(i, v) for (auto &i : (v)) #define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; } #define sortv(v) sort(v.begin(), v.end()) #define all(v) (v).begin(), (v).end() using vi = vector; using vvi = vector; using vvvi = vector; using vvvvi = vector; using ll = long long; using vl = vector; using vvl = vector; using vvvl = vector; using vvvvl = vector; template auto operator<<(ostream &os, const vector &vec)->ostream& { os << vec[0]; for (size_t i = 1; i < vec.size(); i++) { os << ' ' << vec[i]; } os << '\n'; return os; } template auto operator>>(istream &is, vector &vec)->istream& { for (auto &i : vec) { is >> i; } return is; } template auto operator<<(ostream &os, const vector> &vec)->ostream& { for (auto &i : vec) { os << i[0]; for (size_t j = 1; j < i.size(); j++) { os << ' ' << i[j]; } os << '\n'; } return os; } template auto operator>>(istream &is, vector> &vec)->istream& { for (auto &i : vec) { for (auto &j : i) { is >> j; } } return is; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n, m; cin >> m >> n; n <<= 1; vvi graph(n); vvi inv(n); while (m--) { char op1, op2; int a, b; cin >> op1 >> a >> op2 >> b; a--, b--; if (op1 == '-') { a += n >> 1; } if (op2 == '-') { b += n >> 1; } graph[a].push_back((b + (n >> 1)) % n); graph[b].push_back((a + (n >> 1)) % n); inv[(b + (n >> 1)) % n].push_back(a); inv[(a + (n >> 1)) % n].push_back(b); } V vis(n); vi top; function preorder = [&](int i) { vis[i] = true; for (auto j : graph[i]) { if (vis[j]) { continue; } preorder(j); } top.push_back(i); }; rep(i, n) { if (vis[i]) { continue; } preorder(i); } reverse(all(top)); fill(all(vis), false); vi group(n); vi representant(n); int g = 0; function scc = [&](int i) { vis[i] = true; group[i] = g; for (auto j : inv[i]) { if (vis[j]) { continue; } scc(j); } }; repv(i, top) { if (vis[i]) { continue; } scc(i); representant.push_back(i); g++; } rep(i, n >> 1) { if (group[i] == group[i + (n >> 1)]) { cout << "IMPOSSIBLE\n"; return 0; } } fill(all(vis), false); reverse(all(representant)); string ans(n >> 1, ' '); function getans = [&](int i) { vis[i] = true; if (ans[i % (n >> 1)] == ' ') { ans[i % (n >> 1)] = i < (n >> 1) ? '-' : '+'; } repv(j, graph[i]) { if (vis[j] || group[j] != group[i]) { continue; } getans(j); } }; repv(i, representant) { if (vis[i]) { continue; } getans(i); } repv(i, ans) { cout << i << ' '; } cout << '\n'; }