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
str=input().split()
stack=[]
for i in range(len(str)):
	if str[i].isdigit():
		stack.append(int(str[i]))
	else:
		y=stack.pop()
		x=stack.pop()
		if str[i]=='+':
			stack.append(x+y)
		elif str[i]=='-':
			stack.append(x-y)
		elif str[i]=='*':
			stack.append(x*y)
print(stack.pop())
