import sys

a, s, t = "", "", []
for line in sys.stdin:
    a = line.split()
for i in a[0]:
    if i in "()[]":
        s += i
for j in s:
    if len(t) == 0:
        t.append(j)
    else:
        t.pop(-1) if t[-1] + j in ["()", "[]"] else t.append(j)
print("true" if not t else "false")