PAT乙级 1065. 单身狗(25)

//PAT-1-1065
#include <iostream>
#include <algorithm>
#include <string>
#include <math.h>
#include <sstream>
#include <vector>
using namespace std;

int main(){
int n;
cin>>n;
int couple[100000];
for (int i=0; i<100000; i++) {
couple[i]=-1;
}
for (int i=0; i<n; i+=1) {
int a,b;
scanf("%d %d",&a,&b);
couple[a]=b;

couple[b]=a;

}
int m;
cin>>m;
int guest[100000]={0};
for (int i=0; i<m; i++) {
int id;
scanf("%d",&id);
guest[id]+=1;
//cout<<couple[id]<<" ";
if (couple[id]!=-1) {
guest[couple[id]]+=2;
//cout<<guest[couple[id]]<<"\n";
}

}
int count=0;
for (int i=0; i<100000; i++) {
if (guest[i]==1) {
//cout<<i<<" ";
count++;
}
}
cout<<count<<endl;
int f=1;
for (int i=0; i<100000; i++) {
if (guest[i]==1&&f) {
printf("%05d",i);
f=0;
}
else if (guest[i]==1&&!f) {
printf(" %05d",i);
}
}
return 0;
}