n = int(input())
A = input().split()

ans = []

for a in A:
    if a == "+":
        x = ans.pop()
        y = ans.pop()
        ans.append(x + y)
    elif a == "-":
        x = ans.pop()
        y = ans.pop()
        ans.append(y - x)
    else:
        ans.append(int(a))

print(*ans)