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())
A=list(map(str,input().split()))
s=A
now=0

def expr():
    global now
    ans= term()
    while now<n :
        y = term()
        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)]):
        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())