#include <stdio.h>
 
int main(void) {
	int a[56],b[56];
	int c[8][56];
	int n,i,j,r;
	int k=0;
	scanf("%d",&n);
	if(n<6 || n>56 || n%2==1){
		printf("Invalid input");
		return 0;
	}
	for(int i=0;i<n;i++){
		a[i]=i+1;
	}
	for(i=0;i<n;i++){
		scanf("%d",&b[i]);
	}
	r=n/2;
	for(j=1;j<=8;j++){
		for(i=0;i<=n/2+1;i=i+2){
				c[j][i]=a[k];
				c[j][i+1]=a[r];
				r=r+1;
				k++;
				printf("%d %d ",c[j][i],c[j][i+1]);
		}
		break;
	}
	return 0;
}
 

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NgoxCjQKNQoyCjMKNgo=

6
1
4
5
2
3
6