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
ope = {"+": lambda a, b: b + a,
	   "-": lambda a, b: b - a,
	   "*": lambda a, b: b * a}
stack = []

for c in input().split():
	if c in ope:
		stack.append(ope[c](stack.pop(), stack.pop()))
	else:
		stack.append(int(c))

print(stack[-1])