func_code_string: #include <bits/stdc++.h>   using namespace std;   int pow(int a, int b, int c) {     int ret = 1;     for (; b; b >>= 1, a = 1LL * a * a % c)       if (b & 1) ret = 1LL * ret * a % c;     return ret;   }   const int N = 2e3 + 10, M = 4.05e6 + 10;   int h[N], g[N], p[M], n1[M], ee, low[N], dfn[N], dfntot, vis[N], n, m, st[N],       top, id[N], tot, sz[N], ans, dp[N], ok[N];   pair<int, int> e[M];   void ae(int *A, int x, int y) {     p[ee] = y;     n1[ee] = A[x];     A[x] = ee++;   }   void tarjan(int u, int fa) {     vis[u] = 1;     low[u] = dfn[u] = ++dfntot;     st[++top] = u;     for (int i = h[u]; ~i; i = n1[i])       if (p[i] != fa) {         if (!vis[p[i]])           tarjan(p[i], u), low[u] = min(low[u], low[p[i]]);         else           low[u] = min(low[u], dfn[p[i]]);         if (low[p[i]] > dfn[u]) {           ++tot;           while (st[top] != p[i]) id[st[top--]] = tot, sz[tot]++;           id[st[top--]] = tot;           sz[tot]++;         }       }   }   void dfs(int u, int fa) {     dp[u] = sz[u];     for (int i = g[u]; ~i; i = n1[i])       if (p[i] != fa) {         dfs(p[i], u);         dp[u] += dp[p[i]];       }   }   int main() {     scanf( %d%d , &n, &m);     memset(h, -1, sizeof(h));     memset(g, -1, sizeof(g));     int x, y;     for (int i = 1; i <= m; i++) scanf( %d%d , &x, &y), ae(h, x, y), ae(h, y, x);     for (int i = 1; i <= n; i++)       if (!vis[i]) tarjan(i, 0);     ++tot;     while (top) id[st[top--]] = tot, sz[tot]++;     for (int i = 1; i <= n; i++)       for (int j = h[i]; ~j; j = n1[j])         if (id[i] != id[p[j]]) ae(g, id[i], id[p[j]]);     for (int i = 1; i <= tot; i++) ans += sz[i] * (sz[i] - 1);     int ret = 0;     for (int i = 1; i <= tot; i++) {       int tmp = 0;       dfs(i, 0);       for (int j = 1; j <= tot; j++) tmp += (dp[j] - sz[j]) * sz[j];       for (int j = 0; j <= n; j++) ok[j] = 0;       ok[0] = 1;       for (int k = g[i]; ~k; k = n1[k])         for (int j = n; j >= dp[p[k]]; j--) ok[j] |= ok[j - dp[p[k]]];       int mx = 0;       for (int j = 0; j <= n; j++)         if (ok[j]) mx = max(mx, j * (n - sz[i] - j));       ret = max(ret, tmp + mx);     }     printf( %d n , n + ans + ret);     return 0;   }   