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 = raw_input().split(" ")
Stack = list()

def push(x):
    Stack.append(x)

def pop():
    return Stack.pop(-1)

a = 0
b = 0
for i in range(len(S)):
    if S[i] == "+":
        a = pop()
        b = pop()
        push(b + a)
    elif S[i] == "-":
        a = pop()
        b = pop()
        push(b - a)
    elif S[i] == "*":
        a = pop()
        b = pop()
        push(b * a)
    elif S[i] == "/":
        a = pop()
        b = pop()
        push(b / a)
    else:
        push(int(S[i]))

print Stack.pop(-1)