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
input_list = input().rstrip().split(" ")

stack = []
for i in input_list:
    if i in ["+", "-", "*"]:
        num_1 = stack.pop()
        num_2 = stack.pop()
        stack.append(str(eval(num_2 + i + num_1)))
    else:
        stack.append(i)
answer = stack.pop()
print(answer)
