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
ri = raw_input().split()
stack = []
for i in xrange(len(ri)):
  if ri[i] == "+":
    b = stack.pop()
    a = stack.pop()
    stack.append(str(int(a)+int(b)))
  elif ri[i] == "-":
    b = stack.pop()
    a = stack.pop()
    stack.append(str(int(a)-int(b)))
  elif ri[i] == "*":
    b = stack.pop()
    a = stack.pop()
    stack.append(str(int(a)*int(b)))
  else:
    stack.append(ri[i])
print stack.pop()