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

str=raw_input().strip().split()
list=list()


ans=0
for ss in str:
    if ss=="*":
        a=list.pop()
        b=list.pop()
        list.append(a*b)
    elif ss=="+":
        a=list.pop()
        b=list.pop()
        list.append(a+b)

    elif ss=="-":
        a=list.pop()
        b=list.pop()
        list.append(b-a)
        
    else:
        list.append(int(ss))
   
    
print list.pop()
