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
lis = input().split()
st = []
for i in lis:
  if i == "+":
    x = st.pop()
    y = st.pop()
    st.append(x+y)
  elif i == "-":
    x = st.pop()
    y = st.pop()
    st.append(y-x)
  elif i == "*":
    x = st.pop()
    y = st.pop()
    st.append(x*y)
  else:
    st.append(int(i))
print(st[0])  
