Description

Write a program that evaluates a string expression. You will be given that string expression on the first line in the form of numbers and operators separated with a single space from each other. Your job is to take that string expression and calculate the result after evaluating it.
To do that you have to follow a simple rule. If for example we have this string “2 4 * 1 3 -” the first time we meet an operator (*) we have to take all the numbers we have so far (2, 4), apply that operation to them and save the result (8). The next time we meet an operator (-), we again take all of the numbers we have (8, 1, 3) and apply the operator to them in that order (8 – 1 – 3 = 4). At the end, we print the result.
All the numbers will always be integers and the possible operators are “*”, “+”, “-“, “/”. It is important to keep the order of the numbers (especially for “/” and “-” because the order matters). When having a division, you have to round the result to the lower integer.
Input
• Single line: a string containing integers and operators
Output
• Single number: the result after the evaluation
Constrains
• When reaching an operator, it is sure that you will have minimum one number to evaluate
• The string will always end with an operator, so you get one number as a result
• Operators and numbers will always be valid
• There will be no case of division by zero
• There might be negative numbers in the string
Examples
Input Output Comment
6 3 – 2 1 * 5 /
1 6 – 3 = 3
3 * 2 * 1 = 6
6 / 5 = 1
2 2 – 1 * 0 2 – 2 = 0
0 * 1 = 0
10 23 * 4 2 / 30 10 + 100 50 – 2 -1 * 164 10 * 23 = 230
230 / 4 / 2 = 28
28 + 30 + 10 = 68
68 – 100 – 50 = -82
-82 * 2 * -1 = 164
Trust your calculator. It is something to count on…