#include<bits/stdc++.h>
using namespace std;
char in[100], out[100];
int A[1100], B[10100];
int main(){
	for(int I = 1; I<=10; I++){
		
		sprintf(in,".%d.in",I);
        freopen(in,"w",stdout);
		int n, a, i, j, t;
		for(i=0;i<1100;i++) A[i]=0;
		//scanf("%d", &n);
		n = 10000;
		sprintf(in,".%d.in",I);
        freopen(in,"w",stdout);
        printf("%d\n", n);
        for(i=0;i<n;i++){
        	B[i] = rand()%1001;
        	printf("%d\n",B[i]);
		}
        
		sprintf(in,".%d.out",I);
        freopen(in,"w",stdout);
		for(i=0;i<n;i++){
			//scanf("%d", &a);
			a = B[i];
			if(a==0){
				t = 0;
				for(j=1;j<=1000;j++){
					if(A[j]==1){
						if(t>0) printf(" ");
						t++;
						printf("%d", j);
					} 
				}
				if(t==0) printf("-1");
				printf("\n");
			}else{
				A[a] ^= 1;
			}
		}
	}
}