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()
ope = []

for s in S:
  if s.isdigit():
    ope.append(s)
  else:
    a = int(ope.pop())
    b = int(ope.pop())
    if s == '+':
      ope.append(a + b)
    elif s == '-':
      ope.append(b - a)
    else:
      ope.append(a * b)
print(ope[0])
