为什么最后两个点错（经试验他会把两个不联通的点接上）

#include<bits/stdc++.h>
using namespace std;
struct bi{
    int x,y;
}a[1024];
int n,d[1025],pd=0,b[501],qi=501,f[501][501],maxx,minn=501;
void sc(){
    pd=1;
    for(int i=0;i<=n;i++){
        cout<<d[i]<<endl;
    }
}
int dfs(int kai,int wei){
    for(int i=minn;i<=maxx;i++){
        if(f[kai][i]>0){
            f[kai][i]--;
            f[i][kai]--;
            d[wei]=i;
            dfs(i,wei+1);
            if(wei==n) sc();
        }
        if(pd==1) return 0;
    }
}
int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>a[i].x>>a[i].y;
        b[a[i].x]++;
        b[a[i].y]++;
        f[a[i].x][a[i].y]++;
        f[a[i].y][a[i].x]++;
        maxx=max(maxx,max(a[i].x,a[i].y));
        minn=min(minn,min(a[i].x,a[i].y));
    }
    for(int i=minn;i<=maxx;i++){
        if(b[i]%2==1) {qi=i;break;}
    }
    if(qi==501) qi=minn;
    d[0]=qi;
    dfs(qi,1);
    return 0;
}