use std::fmt::format;


fn main() {
    let mut nm = String::new();
    std::io::stdin().read_line(&mut nm).ok();
    let nm: Vec<usize> = nm.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nm[0];
    let m = nm[1];
    let words = (0..n).map(|_| {
            let mut temp = String::new();
            std::io::stdin().read_line(&mut temp).ok();
            let temp = temp.trim();
            temp.chars().collect::<Vec<_>>()
        })
        .collect::<Vec<_>>();

    let a = &words[0];
    let b = &words[1];
    let start = (0..m).filter(|&i| a[i] != b[i]).nth(0).unwrap();
    let end = (0..m).rev().filter(|&i| a[i] != b[i]).nth(0).unwrap();
    let t1 = format!("{}{}{}{}"
        , (0..start).map(|i| a[i].to_string()).collect::<Vec<_>>().join("")
        , (start..=end).map(|i| a[i].to_string()).collect::<Vec<_>>().join("")
        , b[end]
        , (end+1..m).map(|i| a[i].to_string()).collect::<Vec<_>>().join(""))
        .chars().collect::<Vec<_>>();
    let t2 = format!("{}{}{}{}"
        , (0..start).map(|i| a[i].to_string()).collect::<Vec<_>>().join("")
        , (start..=end).map(|i| b[i].to_string()).collect::<Vec<_>>().join("")
        , a[end]
        , (end+1..m).map(|i| a[i].to_string()).collect::<Vec<_>>().join(""))
        .chars().collect::<Vec<_>>();
    let mut result = 0usize;
    let word_ok = |i: usize, t: &Vec<char>| {
        let start = (0..m+1).filter(|&j| j == m || words[i][j] != t[j]).nth(0).unwrap();
        (start..m).map(|j| words[i][j] == t[j+1]).fold(true, |x, y| x && y)
    };
    let temp = (0..n).filter(|&i| word_ok(i, &t1)).count() == n;
    if temp { result += 1; }
    let temp = (0..n).filter(|&i| word_ok(i, &t2)).count() == n;
    if temp { result += 1; }
    println!("{}", result);
}