func_code_string: #include <bits/stdc++.h>   using namespace std;   struct Maxflow {     static const int oo = 100000005;     static const int maxn = 5555 * 2;     static const int maxm = 5555 * 4;     int T, S;     struct node {       int to, nxt, cap;     } ed[maxm * 2];     int head[maxn], cur[maxn], cnt, ans, ndnum;     int h[maxn];     void addedge(int u, int v, int cap) {       ed[cnt].to = v, ed[cnt].cap = cap, ed[cnt].nxt = head[u], head[u] = cnt++;       ed[cnt].to = u, ed[cnt].cap = 0, ed[cnt].nxt = head[v], head[v] = cnt++;     }     bool bfs() {       memset(h, -1, sizeof(h));       queue<int> q;       h[S] = 0, q.push(S);       while (!q.empty()) {         int now = q.front();         q.pop();         for (int i = head[now]; ~i; i = ed[i].nxt) {           if (ed[i].cap && h[ed[i].to] == -1) {             h[ed[i].to] = h[now] + 1;             q.push(ed[i].to);           }         }       }       return h[T] != -1;     }     int dfs(int x, int f) {       if (x == T || f == 0) return f;       int w, used = 0;       for (int i = cur[x]; ~i; i = ed[i].nxt) {         if (h[ed[i].to] == h[x] + 1) {           w = f - used;           w = dfs(ed[i].to, min(w, ed[i].cap));           ed[i].cap -= w;           ed[i ^ 1].cap += w;           if (ed[i].cap) cur[x] = i;           used += w;           if (used == f) return f;         }       }       if (!used) h[x] = -1;       return used;     }     void dinic() {       while (bfs()) {         for (int i = 1; i <= ndnum; i++) {           cur[i] = head[i];         }         ans += dfs(S, oo);       }     }     void init(int s, int t, int num) {       for (int i = 1; i <= num; i++) head[i] = -1;       ans = cnt = 0;       T = t;       S = s;       ndnum = num;     }   } flow;   int n, m;   int a[5111], b[5111];   bool isok(int x) {     flow.init(n + m + 1, n + m + 3, n + m + 3);     int s = n + m + 1, t = n + m + 2, T = n + m + 3;     for (int i = 1; i <= m; i++) {       flow.addedge(i, m + a[i], 1);       flow.addedge(i, m + b[i], 1);     }     for (int i = 1; i <= m; i++) flow.addedge(s, i, 1);     for (int i = 1; i <= n; i++) flow.addedge(m + i, t, x);     flow.addedge(t, T, m);     flow.dinic();     return flow.ans == m;   }   int main() {     scanf( %d%d , &n, &m);     for (int i = 1; i <= m; i++) scanf( %d%d , &a[i], &b[i]);     int l = 0, r = m, ans = m;     while (l <= r) {       int mid = l + r >> 1;       if (isok(mid)) {         ans = mid;         r = mid - 1;       } else         l = mid + 1;     }     printf( %d n , ans);     isok(ans);     for (int i = 0; i < 4 * m; i += 4) {       if (flow.ed[i].cap == 1)         printf( %d %d n , b[i / 4 + 1], a[i / 4 + 1]);       else         printf( %d %d n , a[i / 4 + 1], b[i / 4 + 1]);     }     return 0;   }   