import sys
try:
    import os
    f = open('input.txt', 'r')
    sys.stdin = f
except FileNotFoundError:
    None
from math import sqrt, ceil
input=lambda: sys.stdin.readline().strip()

n=int(input())
s=list(map(str,input().split()))

now=0

# def expr():
#     global now
#     ans= term()
#     while now<n and s[now] not in "+-" :
#         y =  expr()
#         op = s[now]
#         now+=1
#         if op =="+":
#             ans+= y
#         else:
#             ans-=y
#     return ans
#
#
# def term():
#     global now
#     if now >=n:
#         return 0
#     elif n-2 <= now:
#         # print(s[now],now)
#         x = int(s[now])
#         now +=1
#         return x
#     elif s[now].isdecimal() and s[now+1].isdecimal() and s[now+2] in "+-":
#          x = int(s[now])
#          y = int(s[now+1])
#          op = s[now+2]
#          now+=3
#          if op=="+": return x+y
#          return x-y
#     # elif all([s[i].isdecimal() for i in range(now,now+3)]):
#     else:
#
#         x = int(s[now]); now+=1
#         y = term()
#         op = s[now]
#         now+=1
#         if op=="+":return x+y
#         return x-y
#         # now+=1
#         # return int(s[now])
#
#
#
# print(expr())


def expr():
    global now
    x = term()
    ans = x
    if now >=n or s[now] in "+-":
        return x
    y = expr()
    op = s[now] ;now+=1
    if op =="+":return x+y
    return x-y




def term():
    global now
    if n-2 <= now:
        now+=1
        return int(s[now-1])
    if s[now].isdecimal() and s[now+1].isdecimal() and s[now+2] in "+-":
        op= s[now+2]
        now+=3
        if op=="+":
            return int(s[now-3])+ int(s[now-2])
        else:
            return int(s[now-3])-int(s[now-2])
    else:
        now+=1
        return int(s[now-1])

print(expr())