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
def Cal(sym,n1,n2):
    n1 = int(n1)
    n2 = int(n2)
    if sym == '+':
        ans = n1 + n2
    elif sym == '-':
        ans = n1 - n2
    else:
        ans = n1 * n2
        
    return ans

stack = []

for item in raw_input().split():
    if item.isdigit():
        stack.append(item)
    else:
        n2 = stack.pop()
        n1 = stack.pop()
        sym = item
        ans = Cal(sym,n1,n2)
        stack.append(ans)

Ans = stack.pop()

print Ans