#include<stdio.h>
int main()
{
	freopen("energii.in","r",stdin);
	freopen("energii.out","w",stdout);
	int n,c,i;
	scanf("%d%d",&n,&n);
	for(i=0;i<n;i++)
		scanf("%d%d",&c,&c);
	printf("-1");
	return 0;
}