whywhywhy???
代码 ```cpp
#include<bits/stdc++.h>
using namespace std;
int main(){
int a[1001]={0};
int n,m,b;
bool Not_already_out=true;
cin>>n>>m;
for(int i=0;i<m;i++){
cin>>b;
a[b]=1;
}
for(int i=0;i<n-1;i++){
if(a[i]!=1){
cout<<i<<" ";
Not_already_out=false;
}
}
if(Not_already_out==true){
cout<<n;
}
}
