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
from collections import deque

ope={'+':lambda a,b:b+a,'-':lambda a,b:b-a,'*':lambda a,b:b*a}

A=list(map(str,input().split()))

n=len(A)
D=deque()
for i in A:
    if i not in ope:
        D.append(i)
    else:
        D.append(ope[i](int(D.pop()),int(D.pop())))

print(D.pop())
