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
s = input().split()
stk = []
for i in s:
	if i.isdigit():
		stk.append(int(i))
	else:
		a = stk.pop()
		b = stk.pop()
		if i == '+':
			stk.append(b + a)
		elif i == '-':
			stk.append(b - a)
		else:
			stk.append(b * a)
print(stk.pop())

