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

def solve(tokens):
    stack = []

    for token in tokens:
        if token == "+":
            t1 = stack.pop()
            t2 = stack.pop()
            stack.append(t1 + t2)
        elif token == "-":
            t1 = stack.pop()
            t2 = stack.pop()
            stack.append(t2 - t1)
        elif token == "*":
            t1 = stack.pop()
            t2 = stack.pop()
            stack.append(t1 * t2)
        else:
            stack.append(int(token))

    return stack.pop()


def main():
    print solve(raw_input().split())


if __name__ == "__main__":
    main()