bzoj 1191

#include<cstdio>
#include<cctype>
#include<vector>
using namespace std;
int read(){
    char c; while(!isdigit(c=getchar())); int x=c-‘0‘;
    while(isdigit(c=getchar())) x=x*10+c-‘0‘; return x;
}
vector<int> e[1001];
int vis[1001],cos[1001];
bool find(int now,int tme){
    for(int i=0;i<e[now].size();i+=1)
        if(vis[e[now][i]]!=tme){
            vis[e[now][i]]=tme;
            if(!cos[e[now][i]] || find(cos[e[now][i]],tme))
                return cos[e[now][i]]=tme,1;
        }
    return 0;
}
int main(){
    int n=read(),m=read(),ans=0;
    for(int i=1;i<=m;i+=1){
        int x=read(),y=read();
        e[i].push_back(x);
        e[i].push_back(y);
    }
    for(int i=1;i<=m;i+=1)
        if(find(i,i)) ans++; else break;
    printf("%d",ans);
    return 0;
}