import sys if __name__ == '__main__':
    a=input()
    b=int(input())  if b>len(a):  print(-1)  else:
        c=[]  for i in range(len(a)-b+1):     
      if a[i:i+b] not in c:
                c.append(a[i:i+b])  print(a[i:i+b],end=' ')