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
L = list(input().split())
a = []

for i in L:
	if i in ["+","-","*"]:
		c,b = str(a.pop()), str(a.pop())
		b += i + c
		a += [int(eval(b))]
	else:
		a += [int(i)]

print(a.pop())

