n=input()
s=input()
Strls=[]
strls=[]
intls=[]
for i in s:
    if type(i)==str and i.isupper():
        Strls.append(i)
    elif type(i)==str and i.islower():
        strls.append(i)
    else:
        intls.append(i)
# print(Strls)
# print(strls)
# print(intls)
finalls=strls+intls+Strls
print("".join(finalls))