const INF: usize = 1usize << 60;

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 mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<usize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let mut b = String::new();
    std::io::stdin().read_line(&mut b).ok();
    let b: Vec<usize> = b.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let a = (0..n).flat_map(|i| {
            let mut ret = vec![1usize; a[i]+1];
            ret[0] = 0;
            ret
        })
        .collect::<Vec<_>>();
    let b = (0..m).flat_map(|i| {
            let mut ret = vec![1usize; b[i]+1];
            ret[0] = 0;
            ret
        })
        .collect::<Vec<_>>();
    let n = a.len();
    let m = b.len();
    let mut dp = vec![vec![INF; m+1]; n+1];
    dp[0][0] = 0;
    for i in 0..=n {
        for j in 0..=m {
            if i+1 <= n {
                dp[i+1][j] = dp[i+1][j].min(dp[i][j] + 1);
            }
            if j+1 <= m {
                dp[i][j+1] = dp[i][j+1].min(dp[i][j] + 1);
            }
            if i+1 <= n && j+1 <= m {
                dp[i+1][j+1] = dp[i+1][j+1].min(dp[i][j] + if a[i] == b[j] { 0 } else { 1 });
            }
        }
    }
    println!("{}", dp[n][m]);
}