3[a2[bc]]

abcbcabcbcabcbc

s=input().strip()
stack=[]; cur=''; num=0
for ch in s:
    if ch.isdigit(): num=num*10+int(ch)
    elif ch=='[': stack.append((cur,num)); cur=''; num=0
    elif ch==']':
        prev,k=stack.pop(); cur=prev+cur*k
    else: cur+=ch
print(cur)