#很不推荐大家在正赛用try，有点不规范，但可以开阔下思路（
a = int(input())
n = input()
low = ""
up = ""
num = ""
for i in n:
    try :
        p = int(i)#这里我们利用py在int非数字会报错的机制用try写
    except :
        if i == i.lower():
            low += i
        else :
            up += i
    else :
        num += i
print(low + num + up)