？？？？

#include <iostream>
#include <fstream> 
using namespace std;
int n,m,a[1005],x[1005];
bool f;
int main(){
    //freopen("B3842.in","r",stdin);
    //freopen("B3842.out","w",stdout);
    cin>>n>>m;
    for (int i=1;i<=m;i++){
        cin>>a[i];
        x[a[i]]++;
    }
    for (int i=0;i<n;i++){
        if (x[i]==0){
            cout<<i<<" ";f=1;
        }
    }
    if (!f) cout<<n;
    //fclose(stdin);
    //fclose(stdout);
    return 0;
}

没找出来错哪了，可能来个大佬指教一下QWQ