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

def main():
    l = input().split(' ')

    while len(l) > 1:
        idx = 0
        while l[idx] not in ["+", "-", "*"]:
            idx += 1
        res = str(eval(str(l[idx-2] + l[idx] + l[idx-1])))
        l[idx-2] = res
        l.pop(idx-1)
        l.pop(idx-1)

    print(l[0])

main()
