StackMath
In Reverse Polish Notation the operator comes after its two operands, so 3 4 + means 3 + 4. Evaluate an expression written this way using the operators + - * /. Division truncates toward zero.
Input
A single line of space-separated tokens: integers (possibly negative) and the operators + - * /.
Output
Print the value of the expression.
Constraints
1 <= number of tokens <= 10^4 The expression is always valid, never divides by zero, and every intermediate value fits in 32 bits.
Example 1
Input
2 1 + 3 *
Output
9
(2 + 1) * 3 = 9.
Example 2
Input
4 13 5 / +
Output
6
13 / 5 truncates to 2, and 4 + 2 = 6.