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
A = raw_input().split()
S = []
for x in A:
    if x in ['+', '-', '*']:
        b = int(S.pop())
        a = int(S.pop())
        if x == '+':
            S.append(a + b)
        elif x == '-':
            S.append(a - b)
        else:
            S.append(a * b)
    else:
        S.append(x)

print S.pop()