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 Rust (1.15.1) (judge verdict: Accepted)

#[allow(dead_code)]
fn scan<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[allow(dead_code)]
fn scan_split<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().split_whitespace()
        .map(|t| t.parse().ok().unwrap()).collect()
}

#[allow(dead_code)]
fn scan_split_with<T: std::str::FromStr>(ch: char) -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().split(ch)
        .map(|t| t.parse().ok().unwrap()).collect()
}

#[allow(dead_code)]
fn scan_lines<T: std::str::FromStr>(n: usize) -> Vec<T> {
    (0..n).map(|_| scan::<T>()).collect()
}

#[allow(unused_macros)]
macro_rules! scan_as_tuple {
    ( $t:ty ) => {
        (scan::<$t>(),)
    };
    ( $( $t:ty ),* ) => {
        {
            let mut s = String::new();
            std::io::stdin().read_line(&mut s).ok();
            let v = s.trim().split_whitespace();
            let mut it = v;
            let ret = ( $(it.next().unwrap().parse::<$t>().ok().unwrap()),* );
            assert!(it.next() == None, "not all tokens consumed");
            ret
        }
    };
}

fn main() {
    let (a, op, b) = scan_as_tuple![i32, String, i32];
    println!("{}", match op.chars().nth(0).unwrap() {
        '+' => a + b,
        '-' => a - b,
        _ => 0
    });
}