from sys import stdin

monkeys = {}

for line in stdin:
	out = line[:4]
	parts = line[6:].split()
	if len(parts) == 1: parts = int(parts[0])
	monkeys[out] = parts

def get(k):
	m = monkeys[k]
	if type(m) != int:
		a = get(m[0])
		b = get(m[2])
		op = m[1]
		if op == '+': m = a + b
		if op == '-': m = a - b
		if op == '*': m = a * b
		if op == '/': m = a // b
		monkeys[k] = m
	return m

print(get('root'))