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 = input().split()
b = []
for i in range(len(a)):
    if a[i] == "+":
        b[-2] = b[-2] + b[-1]
        b.pop()
    elif a[i] == "-":
        b[-2] = b[-2] - b[-1]
        b.pop()
    elif a[i] == "*":
        b[-2] = b[-2] * b[-1]
        b.pop()
    else:
        b.append(int(a[i]))
print(b[-1])
