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=input().split()
operand=[]
cnt=0

# 1 2 + 3 4 - *
# -> (1 + 2) * (3 - 4)
for s in S:
  if s in '+-*':
    a=operand.pop()
    b=operand.pop()
    x=eval(b+s+a)
    #tmp=operand.pop()+s+operand.pop()
    #print(tmp)
    #x=eval(tmp)
    operand.append(str(x))
  else:
    operand.append(s)

print(operand.pop())

