use std::io::{BufRead, BufReader};
use std::fs::File;

fn is_safe(v:&[u32]) -> bool
{
    let s_diff = if v[0] > v[1] {false} else {true};    

    for n in 1..v.len() {        
        let diff = v[n].abs_diff(v[n - 1]);

        if diff > 3 || diff == 0{
            return false;
        }

        let s_diff2 = if v[n] < v[n-1] {false} else {true};
        if s_diff2 ^ s_diff {
            return false;
        }
        
    }
    return true;
}

fn main (){
    let filename = "../2/input_example.txt";
    // let filename = "../2/input.txt";
    let file = BufReader::new(File::open(filename).expect("Unable to open file"));
    let mut safe: u32 = 0;    

    for line in file.lines() {        
        let wline = line.unwrap();        
        let nums: Vec<u32> = wline.split(' ')
            .filter(|&x| !x.is_empty())
            .map(|x| x.parse().unwrap())
            .collect();
        
        if is_safe(&nums[..]){
            safe += 1;            
        } else {
            for n in 1..nums.len(){               
                let to_test = &[&nums[0..n], &nums[n+1..nums.len()]].concat();
                if is_safe(to_test){
                    safe += 1;                    
                    break;
                }
            }            
        }                    
    }    

    println!("{}", safe);
}