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 = raw_input().split(' ')
st = []
for i in s:
    if i.isdigit():
        st.append(int(i))
    elif i == '+':
        tmp1 = st.pop()
        tmp2 = st.pop()
        st.append(int(tmp1 + tmp2))
    elif i == '-':
        tmp1 = st.pop()
        tmp2 = st.pop()
        st.append(int(tmp2 - tmp1))
    elif i=='*':
        tmp1 = st.pop()
        tmp2 = st.pop()
        st.append(int(tmp1 * tmp2))
print st[0]