Problem:
Score : 100 points

Problem Statement

Joisino wants to evaluate the formula "A op B".
Here, A and B are integers, and the binary operator op is either + or -.
Your task is to evaluate the formula instead of her.

Constraints

1≦A,B≦10^9

op is either + or -.

Input

The input is given from Standard Input in the following format:

A op B

Output

Evaluate the formula and print the result.

Sample Input 1

1 + 2

Sample Output 1

3

Since 1 + 2 = 3, the output should be 3.

Sample Input 2

5 - 7

Sample Output 2

-2

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)

import           Control.Monad
import           Data.IORef
import           Data.List.Split
import           Data.Maybe
import           Data.List

main :: IO ()
main = do
  [a, op, b] <- words <$> getLine
  print $ case op of
    "+" -> toInt a + toInt b
    "-" -> toInt a - toInt b
    _ -> error "error"
  where
    toInt s = read s :: Int