n = input()
st = raw_input()
if n<6:
    var1 =  6-n
    f = 0
    f1=0
    f2=0
    f3=0
    ref3 = "abcdefghijklmnopqrstuvwxyz"
    ref2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    ref1 = "0123456789"
    ref = "!@#$%^&*()-+"
    for i in range(n):
        if st[i] in ref3:
            f=1;
        elif st[i] in ref2:
            f1=1
        elif st[i] in ref1:
            f2=1;
        elif st[i] in ref:
            f3=1;
    var2 =  4-(f1+f2+f3+f)
    print max(var1,var2)
else:
    f = 0
    f1=0
    f2=0
    f3=0
    ref3 = "abcdefghijklmnopqrstuvwxyz"
    ref2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    ref1 = "0123456789"
    ref = "!@#$%^&*()-+"
    for i in range(n):
        if st[i] in ref3:
            f=1;
        elif st[i] in ref2:
            f1=1
        elif st[i] in ref1:
            f2=1;
        elif st[i] in ref:
            f3=1;
    print 4-(f1+f2+f3+f)