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
ops = {"+":lambda x,y: y+x, "-":lambda x,y: y-x, "*":lambda x,y: y*x}
stack = []
for a in input().split():
    stack.append(ops[a](stack.pop(), stack.pop()) if a in ops else int(a))
print(stack.pop())
