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
#!/usr/bin/env python
# -*- coding:utf-8 -*-
#from __future__ import print_function
import time
import sys
import io
import re
import math
start = time.clock()
i = 0
l=map(str, raw_input().split())
k=[]
for i in l:
    if i=='-' or i=='+' or i=='*':
        t=k.pop()
        s=k.pop()
        u=str(s)+i+str(t)
        k.append(eval(u))
    else:
        k.append(i)
print k[0]