Example

Input

5 3
4
2
5


Output

5
2
4
1
3
#include<cstdio>
int n,m,i,u[999999],a[999999];
int main(){
  scanf("%d%d",&n,&m);
  for(i=0;i<m;i++) scanf("%d",a+i+1);
  for(;i>0;i--) if(!u[a[i]]) printf("%d\n",a[i]),u[a[i]]=1;
  for(;i<n;i++) if(!u[i+1]) printf("%d\n",i+1);
  return 0;
}