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
l=map(str,raw_input().split())
chk=[]
op='-+*'
while len(l):
    k=l.pop(0)
    if k in op:
        b=chk.pop()
        a=chk.pop()
        chk.append(str(eval(a+k+b)))
    else:
        chk.append(k)
print chk[0]