func_code_string: #include <bits/stdc++.h>   const int N = 41;   long long bin_p(long long a, long long b) {     if (!b) return 1;     if (b % 2 == 0) {       long long cur = bin_p(a, b / 2);       return cur * cur;     }     return a * bin_p(a, b - 1);   }   long long color[N];   std::vector<long long> g[N];   long long g1[N], cmpSz = 0;   bool fl = false;   void dfs(int v, int clr = 1) {     color[v] = clr;     for (auto e : g[v]) {       if (color[e] == 0) {         color[e] = (3 - clr);         dfs(e, 3 - clr);       }       if (color[e] == clr) {         fl = true;       }     }   }   const long long LEFT = 22;   const long long MASK_LEFT = (1LL << LEFT) - 1,                   MASK_RIGHT = ((1LL << 40) - 1) ^ MASK_LEFT;   long long dp1[1LL << 21], dp2[1LL << 21];   int main() {     std::ios::sync_with_stdio(false);     std::cin.tie(0);     int n, m;     std::cin >> n >> m;     for (int i = 0; i < m; ++i) {       int a, b;       std::cin >> a >> b;       --a;       --b;       g[a].push_back(b);       g[b].push_back(a);       g1[a] |= (1LL << b);       g1[b] |= (1LL << a);     }     long long isolated = 0;     for (int i = 0; i < n; ++i) {       if (!color[i]) {         dfs(i);         cmpSz++;       }       if (g[i].size() == 0) isolated++;     }     long long answ = (1LL << n);     if (m == 0) {       answ -= (1LL << n);     }     if (!fl) {       answ += (1LL << cmpSz);     }     answ += 2LL * (1LL << isolated);     answ -= (1LL << cmpSz);     for (long long mask = 0; mask < (1 << std::max(0LL, (n - LEFT))); ++mask) {       long long realMask = (mask << LEFT), adMask = 0;       for (long long j = 0; j < n; ++j) {         if ((realMask >> j) & 1) {           adMask |= g1[j];         }       }       if ((adMask & realMask) == 0) {         dp2[mask]++;       }     }     for (long long j = 0; j < std::max(0LL, n - LEFT); ++j) {       for (long long msk = 0; msk < (1LL << std::max(0LL, (n - LEFT))); ++msk) {         if (((msk >> j) & 1)) {           dp2[msk] += dp2[msk ^ (1LL << j)];         }       }     }     for (long long mask = 0; mask < (1 << std::min((long long)n, LEFT)); ++mask) {       long long adMask = 0;       for (long long j = 0; j < n; ++j) {         if ((mask >> j) & 1) {           adMask |= g1[j];         }       }       if ((adMask & mask) == 0) {         answ -= 2 * dp2[(adMask ^ ((1LL << n) - 1)) >> LEFT];       }     }     std::cout << answ;   }   