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
a=[]
for i in input().split():
	if i=='+':
		a[len(a)-2]=int(a[len(a)-2])+int(a[len(a)-1])
		a.pop()
	elif i=='-':
		a[len(a)-2]=int(a[len(a)-2])-int(a[len(a)-1])
		a.pop()
	elif i=='*':
		a[len(a)-2]=int(a[len(a)-2])*int(a[len(a)-1])
		a.pop()
	else :
		a.append(i)

print(a[0])
