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
a=input().split()

ls=[]
ln=len(a)

for i in range(ln):
    if a[i]=="+":
        ls[-2]+=ls[-1]
        ls.pop()
    elif a[i]=="-":
        ls[-2]-=ls[-1]
        ls.pop()
    elif a[i]=="*":
        ls[-2]*=ls[-1]
        ls.pop()
    else:
        ai=int(a[i])
        ls.append(ai)
        
print(ls[-1])
