import operator
arr = ['+',2,2,'-',1]
ops = {'+': sum, '-':operator.sub}
res = 0
cur_op = None
for x in arr:
    if type(x) == int:
        if cur_op == sum:
            res = cur_op([res, x])
        else:
            res = cur_op(res, x)
    else:
        cur_op = ops.get(x)

print(res)