S = input()
n = len(S)

Stacks = [[], []]
OP = []
depth = 0
for i in range(n):
    if '0' <= S[i] <= '9':
        Stacks[depth].append(int(S[i]))
    elif S[i] == '(':
        depth += 1
    elif S[i] == ')':
        a = Stacks[depth].pop()
        depth -= 1
        Stacks[depth].append(a)
    else:
        OP.append(S[i])
    if len(Stacks[depth]) == 2:
        a = Stacks[depth].pop()
        b = Stacks[depth].pop()
        op = OP.pop()
        if op == '+':
            b += a
        elif op == '-':
            b -= a
        Stacks[depth].append(b)
print(Stacks[0][0])