class Stack:
    def __init__(self):
        self.items = []

    def isEmpty(self):
        return self.size() == 0

    def push(self, item):
        self.items.append(item)

    def pop(self):
        return self.items.pop()

    def peek(self):
        return self.items[-1]

    def size(self):
        return len(self.items)


seq = input().split()
s = Stack()
for letter in seq:
    if letter.isdigit():
        s.push(int(letter))
    else:
        n2 = s.pop()
        n1 = s.pop()
        n3 = 0
        if letter == '+':
            n3 = n1 + n2
        elif letter == '-':
            n3 = n1 - n2
        elif letter == '*':
            n3 = n1 * n2
        elif letter == '/':
            n3 = n1 // n2
        s.push(n3)

print(s.pop())