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
inp = map(str, raw_input().split())
s = []
for i in inp:
    if   i == "+": s.append( s.pop(-2) + s.pop(-1) )
    elif i == "-": s.append( s.pop(-2) - s.pop(-1) )
    elif i == "*": s.append( s.pop(-2) * s.pop(-1) )
    else: s.append(int(i))
print s[0]