func_code_string: #include <bits/stdc++.h>   using namespace std;   const int mod = 1000000007;   int n, m;   int clauses[123123][2];   vector<int> uses[123123];   bool vis[123123];   vector<int> chain[123123];   int counter;   vector<pair<long long, long long>> dips;   long long ans;   int rightc(int cnr) {     int xnr = abs(clauses[cnr][1]);     if (uses[xnr].size() == 2) {       return uses[xnr][0] == cnr ? uses[xnr][1] : uses[xnr][0];     } else {       return 0;     }   }   void load() {     cin >> n >> m;     int k;     for (int i = 1; i <= n; ++i) {       cin >> k;       for (int j = 0; j < k; ++j) {         cin >> clauses[i][j];         uses[abs(clauses[i][j])].push_back(i);       }     }   }   void dfs(int cnr, int from) {     if (vis[cnr]) {       return;     }     vis[cnr] = 1;     if (abs(clauses[cnr][1]) == from) {       swap(clauses[cnr][0], clauses[cnr][1]);     }     chain[counter].push_back(cnr);     dfs(rightc(cnr), abs(clauses[cnr][1]));   }   void dfs2(int cnr, int from, int f) {     if (vis[cnr]) {       return;     }     vis[cnr] = 1;     if (!clauses[cnr][1]) {       if (!f) {         swap(clauses[cnr][0], clauses[cnr][1]);       }     } else {       if (abs(clauses[cnr][1]) == from) {         swap(clauses[cnr][0], clauses[cnr][1]);       }     }     chain[counter].push_back(cnr);     dfs2(rightc(cnr), abs(clauses[cnr][1]), 1);   }   void buildChains() {     vis[0] = 1;     for (int i = 1; i <= m; ++i)       if (uses[i].size() == 1 && !vis[uses[i][0]]) {         dfs(uses[i][0], i);         ++counter;       }     for (int i = 1; i <= m; ++i)       if (uses[i].size() == 2) {         if (!vis[uses[i][0]] && !clauses[uses[i][0]][1]) {           dfs2(uses[i][0], i, 0);           ++counter;         }         if (!vis[uses[i][1]] && !clauses[uses[i][1]][1]) {           dfs2(uses[i][1], i, 0);           ++counter;         }       }     for (int i = 1; i <= n; ++i)       if (!vis[i]) {         dfs(i, abs(clauses[i][0]));         ++counter;       }   }   long long dp[123123][2][2][2];   int val(int i, int j, int nr) {     int v1 = i;     if (clauses[nr][0] < 0) {       v1 = 1 - v1;     }     if (clauses[nr][0] == 0) {       v1 = 0;     }     int v2 = j;     if (clauses[nr][1] < 0) {       v2 = 1 - v2;     }     if (clauses[nr][1] == 0) {       v2 = 0;     }     return (v1 | v2);   }   void cleaar(int si) {     for (int i = 0; i < si; ++i)       for (int j = 0; j < 2; ++j)         for (int l = 0; l < 2; ++l)           for (int k = 0; k < 2; ++k) dp[i][j][l][k] = 0;   }   void consider(int nr) {     if (chain[nr].size() == 1 &&         abs(clauses[chain[nr][0]][0]) == abs(clauses[chain[nr][0]][1])) {       if (clauses[chain[nr][0]][0] == clauses[chain[nr][0]][1]) {         dips.push_back(make_pair(1, 1));       } else {         dips.push_back(make_pair(0, 2));       }       return;     }     cleaar(chain[nr].size());     int fi = chain[nr][0];     for (int i = 0; i < 2; ++i)       for (int j = 0; j < 2; ++j) dp[0][i][j][val(i, j, fi)] = 1;     for (int i = 0; i < chain[nr].size() - 1; ++i)       for (int j = 0; j < 2; ++j)         for (int l = 0; l < 2; ++l)           for (int k = 0; k < 2; ++k) {             dp[i + 1][j][0][val(l, 0, chain[nr][i + 1]) ^ k] += dp[i][j][l][k];             dp[i + 1][j][0][val(l, 0, chain[nr][i + 1]) ^ k] %= mod;             dp[i + 1][j][1][val(l, 1, chain[nr][i + 1]) ^ k] += dp[i][j][l][k];             dp[i + 1][j][1][val(l, 1, chain[nr][i + 1]) ^ k] %= mod;           }     int si = chain[nr].size();     if (!clauses[chain[nr][0]][0] && !clauses[chain[nr][si - 1]][1]) {       dips.push_back(make_pair(dp[si - 1][0][0][0], dp[si - 1][0][0][1]));       return;     }     if (!clauses[chain[nr][si - 1]][1]) {       long long r0 = (dp[si - 1][0][0][0] + dp[si - 1][1][0][0]) % mod;       long long r1 = (dp[si - 1][0][0][1] + dp[si - 1][1][0][1]) % mod;       dips.push_back(make_pair(r0, r1));       return;     }     if (abs(clauses[chain[nr][0]][0]) != abs(clauses[chain[nr][si - 1]][1])) {       long long r0 = (dp[si - 1][0][0][0] + dp[si - 1][1][1][0] +                       dp[si - 1][0][1][0] + dp[si - 1][1][0][0]) %                      mod;       long long r1 = (dp[si - 1][0][0][1] + dp[si - 1][1][1][1] +                       dp[si - 1][0][1][1] + dp[si - 1][1][0][1]) %                      mod;       dips.push_back(make_pair(r0, r1));       return;     }     long long r0 = (dp[si - 1][0][0][0] + dp[si - 1][1][1][0]) % mod;     long long r1 = (dp[si - 1][0][0][1] + dp[si - 1][1][1][1]) % mod;     dips.push_back(make_pair(r0, r1));   }   void makeAns() {     long long a = dips[0].first;     long long b = dips[0].second;     for (int i = 1; i < counter; ++i) {       long long c = (a * dips[i].first + b * dips[i].second) % mod;       long long d = (a * dips[i].second + b * dips[i].first) % mod;       a = c;       b = d;     }     ans = b;     for (int i = 1; i <= m; ++i)       if (uses[i].empty()) {         ans *= 2;         ans %= mod;       }   }   void debug() {     return;     for (int i = 0; i < counter; ++i) {       cerr << i <<   :  ;       for (int ind : chain[i]) {         cerr <<  (  << clauses[ind][0] <<  ,   << clauses[ind][1] <<  )  ;       }       cerr << endl;     }     for (auto tmp : dips) {       cerr << tmp.first <<     << tmp.second << endl;     }   }   int main() {     ios_base::sync_with_stdio(0);     load();     buildChains();     for (int i = 0; i < counter; ++i) {       consider(i);     }     debug();     makeAns();     cout << ans << endl;   }   