import sys
readline=sys.stdin.readline

ans_lst=[]
for n in readline().rstrip()[::-1]:
    ans_lst.append(n)
    if len(ans_lst)%4==3:
        ans_lst.append(",")
if ans_lst[-1]==",":
    ans_lst.pop()
ans_lst=ans_lst[::-1]
print(*ans_lst,sep="")