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 = input().split()
b =[]

for i in a:
    if i.isdigit():
        b.append(i)
    else:
        ans = str(eval(b.pop(len(b)-2) + i + b.pop()))
        b.append(ans)
    #print(b)
print(b.pop())

