#include <cstdio>#include <cstring>#include <vector>#include <queue>using namespace std;const int INF=0x3f3f3f3f;const int MAX_V=20010;struct edge{int to,cap,rev;}; vector<edge> G[MAX_V];int level[MAX_V],iter[MAX_V];void add_edge(int from,int to,int cap){    G[from].push_back((edge){to,cap,G[to].size()});    G[to].push_back((edge){from,0,G[from].size()-1});}void bfs(int s){    memset(level,-1,sizeof(level));    queue<int> que;    level[s]=0;    que.push(s);    while(!que.empty()){        int v=que.front(); que.pop();        for(int i=0;i<G[v].size();i++){            edge &e=G[v][i];            if(e.cap>0&&level[e.to]<0){                level[e.to]=level[v]+1;                que.push(e.to);            }        }    }}int dfs(int v,int t,int f){    if(v==t)return f;    for(int &i=iter[v];i<G[v].size();i++){        edge &e=G[v][i];        if(e.cap>0&&level[v]<level[e.to]){            int d=dfs(e.to,t,min(f,e.cap));            if(d>0){                e.cap-=d;                G[e.to][e.rev].cap+=d;                return d;            }        }    }return 0;}int max_flow(int s,int t){    int flow=0;    for(;;){        bfs(s);        if(level[t]<0)return flow;        memset(iter,0,sizeof(iter));        int f;        while((f=dfs(s,t,INF))>0){            flow+=f;        }    }}const int MAX_M=10010;const int MAX_N=10010;int N,M;int e[MAX_M][2];bool check(int x){    int s=0,t=N+M+1;    for(int i=0;i<=t;i++)G[i].clear();    for(int i=1;i<=N;i++)add_edge(s,i,x);    for(int i=1;i<=M;i++){        add_edge(e[i][0],i+N,1),add_edge(e[i][1],i+N,1);        add_edge(i+N,t,1);    }return max_flow(s,t)==M;}int main(){    while(~scanf("%d%d",&N,&M)){        for(int i=1;i<=M;i++)scanf("%d%d",&e[i][0],&e[i][1]);        int l=1,r=M,ans=0;        while(l<=r){            int mid=(l+r)>>1;            if(check(mid))ans=mid,r=mid-1;            else l=mid+1;        }printf("%d\n",ans);    }return 0;}