刘汝佳坑害小萌新!!!

#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
using namespace std;

const int maxn=10000 + 10;
const int maxm=100000 + 10;
int head[maxn],color[maxn];
int en=0,n,m;
queue<int>q;

struct edge
{
    int v,next;
}e[maxm];

inline void add(int u,int v) {
    e[en].next=head[u];
    e[en].v=v;
    head[u]=en++;
}

inline void read(int &a) {
  int c;  a=0;
  while((c=getchar())) if(c>='0'&&c<='9') break;
  do {
      a=a*10+c-'0';
      c=getchar();
  }while(c>='0'&&c<='9');
}

int main() {
    //freopen("in.in","r",stdin);
    int u,v,S,black,ans=0;
    memset(head,-1,sizeof(head));
    read(n); read(m);
    for(int i=0;i<m;i++) {
        read(u); read(v);
        add(u,v); add(v,u);
    }
    for(int s=1;s<=n;s++) if(!color[s]) {
        S=black=1; color[s]=1; q.push(s);
        while(!q.empty()) {
            int u=q.front(); q.pop();
            for(int i=head[u];i!=-1;i=e[i].next) {
                int v=e[i].v;
                if(color[u]==color[v]) return 0&printf("Impossible\n");
                if(!color[v]) {
                    color[v]=3-color[u];
                    q.push(v);
                    if(color[v]&1) black++;
                    S++;
                }
            }
        }
        int x=min(S-black,black);
        ans+=x;
    }
    printf("%d\n",ans);
    return 0;
}