func_code_string: #include <bits/stdc++.h>   using namespace std;   const int mo = 1000000007;   int x, k, X, Y, n, m, u[100005];   long long ans[2];   int f[2], g[2][2][2], G[2][2][2], vis[100005];   vector<int> a[100005], A[100005], e[100005], w[100005];   void dfs(int x) {     if (vis[x]) return;     vis[x] = 1;     memset(G, 0, sizeof G);     int j = a[x][0] == Y, i = j ^ 1;     if (a[x].size() == 1) {       for (int p = 0; p < 2; ++p)         for (int q = 0; q < 2; ++q)           for (int k = 0; k < 2; ++k)             (G[p][q][k ^ q ^ w[x][0]] += g[p][q][k]) %= mo;       memcpy(g, G, sizeof G);       dfs(e[x][0]);     } else {       for (int p = 0; p < 2; ++p)         for (int q = 0; q < 2; ++q)           for (int k = 0; k < 2; ++k) {             if (X == a[x][j]) {               int t = p;               (G[p][t][k ^ ((q ^ w[x][i]) | (t ^ w[x][j]))] += g[p][q][k]) %= mo;             } else {               for (int t = 0; t < 2; ++t)                 (G[p][t][k ^ ((q ^ w[x][i]) | (t ^ w[x][j]))] += g[p][q][k]) %=                     mo;             }           }       Y = a[x][j];       memcpy(g, G, sizeof G);       if (A[Y][0] != x)         dfs(A[Y][0]);       else if (A[Y].size() == 2)         dfs(A[Y][1]);     }   }   int main() {     scanf( %d%d , &n, &m);     for (int i = 1; i <= n; ++i) {       for (scanf( %d , &k); k; --k) {         scanf( %d , &x);         a[i].push_back(abs(x));         w[i].push_back(x < 0);         A[abs(x)].push_back(i);       }     }     ans[0] = 1;     ans[1] = 0;     for (int i = 1; i <= m; ++i)       if (A[i].size() == 2 && A[i][0] != A[i][1]) {         ++u[A[i][0]];         ++u[A[i][1]];         e[A[i][0]].push_back(A[i][1]);         e[A[i][1]].push_back(A[i][0]);       } else if (!A[i].size()) {         ans[0] = ans[0] * 2 % mo;       }     for (int i = 1; i <= n; ++i)       if (!vis[i]) {         if (!e[i].size()) {           vis[i] = 1;           f[0] = f[1] = 0;           if (a[i].size() == 1) {             f[0] = f[1] = 1;           } else {             if (a[i][0] != a[i][1]) {               for (int p = 0; p < 2; ++p)                 for (int q = 0; q < 2; ++q) ++f[(p ^ w[i][0]) | (q ^ w[i][1])];             } else {               for (int p = 0; p < 2; ++p) ++f[(p ^ w[i][0]) | (p ^ w[i][1])];             }           }           long long pp = f[0] * ans[0] + f[1] * ans[1],                     qq = f[1] * ans[0] + f[0] * ans[1];           ans[0] = pp % mo;           ans[1] = qq % mo;         } else if (u[i] == 1) {           if (a[i].size() == 1 || A[a[i][0]].size() == 1)             X = Y = a[i][0];           else             X = Y = a[i][1];           memset(g, 0, sizeof g);           g[0][0][0] = g[1][1][0] = 1;           dfs(i);           f[0] = f[1] = 0;           for (int p = 0; p < 2; ++p)             for (int q = 0; q < 2; ++q)               for (int k = 0; k < 2; ++k) (f[k] += g[p][q][k]) %= mo;           long long pp = f[0] * ans[0] + f[1] * ans[1],                     qq = f[1] * ans[0] + f[0] * ans[1];           ans[0] = pp % mo;           ans[1] = qq % mo;         }       }     for (int i = 1; i <= n; ++i)       if (!vis[i]) {         X = Y = a[i][0];         memset(g, 0, sizeof g);         g[0][0][0] = g[1][1][0] = 1;         dfs(i);         f[0] = f[1] = 0;         for (int p = 0; p < 2; ++p)           for (int q = 0; q < 2; ++q)             for (int k = 0; k < 2; ++k) (f[k] += g[p][q][k]) %= mo;         long long pp = f[0] * ans[0] + f[1] * ans[1],                   qq = f[1] * ans[0] + f[0] * ans[1];         ans[0] = pp % mo;         ans[1] = qq % mo;       }     printf( %lld n , ans[1] % mo);     return 0;   }   