+a    # Lock resource a
+b    # Lock resource b
-a    # Unlock resource a
-b    # Unlock resource b
---   # Thread separator
+b    # Lock resource b
-b    # Unlock resource b

+a
-a
---
+a
-a

+a
+b
-b
-a
---
+b
+a
-a
-b

+a
+b
-a
-b
---
+a
+b
-b
-a

+a
+b
-b
-a
---
+b
+c
-c
-b
---
+c
+a
-a
-c

1: 1 space
2: 1 tab
3: 1 tab + 1 space
4: 2 tabs

import sys
V=set()
t=[[[]]]
for r in sys.stdin:
 r=r.strip()
 if'---'==r:t.append([[]])
 else:v=r[1:];V.add(v);l=t[-1][-1];t[-1].append(l+[v]if'+'==r[0]else filter(lambda x:x!=v,l))
s=lambda l:s(l[1:])+map(lambda x:(l[0],x),l[1:])if 1<len(l)else[]
E=reduce(set.union,map(lambda x:set(sum(map(s,x),[])),t),set())
for v in V:
 k=set();q=[v]
 while 0<len(q):
    u=q.pop(0)
    if u in k:continue
    k.add(u)
    for x,y in E:
     if u==x:
        if y in k:print':(';sys.exit()
        else:q.append(y)
print':)'