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
n=map(str,raw_input().split())
a=[]
ai=0
for i in n:
    if i=="+" :
        a.append(a[ai-1]+a[ai-2])
        a.pop(ai-1);a.pop(ai-2)
        ai-=1
    elif i=="-":
        a.append(a[ai-2]-a[ai-1])
        a.pop(ai-1);a.pop(ai-2)
        ai-=1
    elif i=="*":
        a.append(a[ai-1]*a[ai-2])
        a.pop(ai-1);a.pop(ai-2)
        ai-=1
    else:
        a.append(int(i))
        ai+=1
print(a[0])