Notes

Template in C

Constraints

2 ≤ the number of operands in the expression ≤ 100
1 ≤ the number of operators in the expression ≤ 99
-1 × 109 ≤ values in the stack ≤ 109

Input

An expression is given in a line. Two consequtive symbols (operand or operator) are separated by a space character.

You can assume that +, - and * are given as the operator and an operand is a positive integer less than 106

Output

Print the computational result in a line.

Examples

Input

1 2 +


Output

3


Input

1 2 + 3 4 - *


Output

-3
#coding:utf-8
#1_3_A
formula = input().split()
stack = []
for char in formula:
    if char.isdigit():
        stack.append(char)
    else:
        ans = str(eval(stack.pop(len(stack)-2) + char + stack.pop()))
        stack.append(ans)
print(stack.pop())