题解 | #矩阵乘法计算量估算#

import functools
import itertools
import sys

def multipleTimes(s1,s2):
    ret= s1[0] * s2[1] * s1[1]
    if len(s1) > 2:
        ret += s1[2]
    if len(s2) > 2:
        ret += s2[2]
    return ret
   
multipleShapes = lambda s1, s2: [s1[0], s2[1], multipleTimes(s1, s2)]

numbers = int(input())
shapes = []
rules = ""
for line in sys.stdin:
    if len(shapes) < numbers:
        shapes.append([int(each) for each in line.split()])
    else:
        rules = line
        break

assert rules.count("(") == rules.count(")")

rule_iter = iter(rules)


def count_unit(pre_shapes):
    ret = functools.reduce(multipleShapes, pre_shapes)
    return ret

def count_times(rule_iter, pre_shapes):
    while True:
        try:
            tmp = next(rule_iter)
            if tmp >= "A" and tmp <= "Z":
                pre_shapes.append(shapes[int(ord(tmp) - ord('A'))])
            elif tmp == ")":
                return count_unit(pre_shapes)
            elif tmp == "(":
                unit_shapes = []
                pre_shapes.append(count_times(rule_iter, unit_shapes))
            else:
                pass
        except StopIteration as e:
            return

pre_shapes = []
res = count_times(rule_iter,pre_shapes)
print(pre_shapes[0][2])