N = int(input())
pol = input().split()
stack = []
for buf in pol:
    if str.isdecimal(buf):
        stack.append(buf)
    else:
        a = int(stack.pop(-1))
        b = int(stack.pop(-1))
        if buf == "+":
            ans = b + a
        elif buf == "-":
            ans = b - a
        elif buf == "*":
            ans = b * a
        else:
            ans = b / a
        stack.append(ans)
print(stack.pop(-1))