这个数据有点水啊……

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
int n,m;
int head[101],total;
struct E
{
    int to,inext;
}edge[30010];
void adde(int x,int y)
{
    total++;
    edge[total].to=y;
    edge[total].inext=head[x];
    head[x]=total;
}
int match[101];
bool check[101];
bool erfentu(int u)
{
    for(int i=head[u];i;i=edge[i].inext)
    {
        int v=edge[i].to;
        if(!check[v])
        {
            check[v]=true;
            if(match[v]==-1 || erfentu(match[v]))
            {
                match[u]=v;
                match[v]=u;
                return true;
            }
        }
    }
    return false;
}
int main()
{
    ios::sync_with_stdio(false);
    cin>>m>>n;
    while(1)
    {
        int x,y;
        cin>>x>>y;
        if(x==-1 && y==-1) break;
        adde(x,y);
        adde(y,x);
    }
    memset(match,-1,sizeof(match));
    int ans=0;
    for(int i=1;i<=n;i++)
    {
        if(match[i]==-1)
        {
            memset(check,0,sizeof(check)); //没有加这句话都能有91分……
            if(erfentu(i)) ans++;
        }
    }
    if(ans==0) {cout<<"No Solution!"<<endl;return 0;}
    cout<<ans<<endl;
    for(int i=1;i<=m;i++)
    {
        if(match[i]==-1) continue;
        cout<<i<<" "<<match[i]<<endl;
    }
    return 0;
}