#include<bits/stdc++.h>
#define int long long
using namespace std;
int k;
signed main(){
int p,n;
cin>>p>>n;
if (p==1){
cout<<n+1<<endl;
int p=-1;
for (int i = 0;i<n-1;i++){
int x;
cin>>x;
if (p==-1) cout<<x+1<<endl;
else{
cout<<p+1<<endl;
}
p = x;
}
}
else{
vector<int> n1;
n1.resize(n);
vector<int> n2;
vector<vector<int> > n3;
n3.resize(n);
for (int i = 0;i<n1.size();i++) {
cin>>n1[i];
n1[i]--;
if (n1[i]==i) n3[i].push_back(i);
else{
n3[i].push_back(n1[i]);
n3[n1[i]].push_back(i);
}
}
for (int i = 0;i<n;i++){
if (n3[i].size()==1) n2.push_back(i);
}
if (n2.size()==1) cout<<n2[0]<<" "<<n2[0]<<endl;
else cout<<n2[0]<<" "<<n2[1]<<"\n";
}
}
