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 = []

W = raw_input().split()
    
for word in W:
    if word == "+":
        s1 = S.pop()
        s2 = S.pop()
        S.append(s1 + s2)
    elif word == "-":
        s1 = S.pop()
        s2 = S.pop()
        S.append(s2 - s1)
    elif word == "*":
        s1 = S.pop()
        s2 = S.pop()
        S.append(s2 * s1)
    else:
        S.append(int(word))

print S.pop()