import sys
from collections import deque
input = sys.stdin.readline
N = int(input())
command_list = [input().rstrip().split() for _ in range(N)]
stack = deque()
register = 0
index = 0
while index < N:
command = command_list[index]
C = command[0]
if C == 'PUSH':
x = int(command[1])
stack.append(x)
elif C == 'STORE':
register = stack.pop()
elif C == 'LOAD':
stack.append(register)
elif C == 'PLUS':
x1 = stack.pop()
x2 = stack.pop()
stack.append(x1 + x2)
elif C == 'TIMES':
x1 = stack.pop()
x2 = stack.pop()
stack.append(x1 * x2)
elif C == 'IFZERO':
x = stack.pop()
n = int(command[1])
if x == 0:
index = n
continue
elif C == 'DONE':
print(stack[-1])
break
index += 1
