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
x = input().split()
a = []
for i, j in enumerate(x):
    if j == "+":
        a[-2] += a[-1]
        a.pop()
    elif j == "-":
        a[-2] -= a[-1]
        a.pop()
    elif j == "*":
        a[-2] *= a[-1]
        a.pop()
    else:
        a.append(int(j))
print(a[0])
