pub use __cargo_equip::prelude::*;

use chminmax::chmin;
use mvec::mvec;
#[allow(unused_imports)]
use proconio::{
    input,
    marker::{Bytes, Chars, Usize1},
};

const INF: usize = 1 << 60;

fn main() {
    input! {
        n: usize,
        m: usize,
        a: [usize; n],
        b: [usize; m],
    }
    let f = |a| {
        let mut c = vec![];
        for &x in &a {
            c.push(0);
            c.extend(vec![1; x]);
        }
        c
    };
    let a = f(a);
    let b = f(b);
    let n = a.len();
    let m = b.len();
    let mut dp = mvec![INF; n + 1; m + 1];
    dp[0][0] = 0;
    for i in 0..=n {
        for j in 0..=m {
            if i < n {
                chmin!(dp[i + 1][j], dp[i][j] + 1);
            }
            if j < m {
                chmin!(dp[i][j + 1], dp[i][j] + 1);
            }
            if i < n && j < m {
                chmin!(
                    dp[i + 1][j + 1],
                    dp[i][j] + if a[i] == b[j] { 0 } else { 1 }
                );
            }
        }
    }
    println!("{}", dp[n][m]);
}

// The following code was expanded by `cargo-equip`.

///  # Bundled libraries
/// 
///  - `chminmax 0.1.0 (path+████████████████████████████████████████████████████)` published in **missing** licensed under `CC0-1.0` as `crate::__cargo_equip::crates::chminmax`
///  - `mvec 0.1.0 (path+████████████████████████████████████████████████)`         published in **missing** licensed under `CC0-1.0` as `crate::__cargo_equip::crates::mvec`
#[cfg_attr(any(), rustfmt::skip)]
#[allow(unused)]
mod __cargo_equip {
    pub(crate) mod crates {
        pub mod chminmax {pub use crate::__cargo_equip::macros::chminmax::*;#[macro_export]macro_rules!__cargo_equip_macro_def_chminmax_min{($a:expr$(,)*)=>{{$a}};($a:expr,$b:expr$(,)*)=>{{std::cmp::min($a,$b)}};($a:expr,$($rest:expr),+$(,)*)=>{{std::cmp::min($a,$crate::__cargo_equip::crates::chminmax::min!($($rest),+))}};}macro_rules!min{($($tt:tt)*)=>(crate::__cargo_equip_macro_def_chminmax_min!{$($tt)*})}#[macro_export]macro_rules!__cargo_equip_macro_def_chminmax_max{($a:expr$(,)*)=>{{$a}};($a:expr,$b:expr$(,)*)=>{{std::cmp::max($a,$b)}};($a:expr,$($rest:expr),+$(,)*)=>{{std::cmp::max($a,$crate::__cargo_equip::crates::chminmax::max!($($rest),+))}};}macro_rules!max{($($tt:tt)*)=>(crate::__cargo_equip_macro_def_chminmax_max!{$($tt)*})}#[macro_export]macro_rules!__cargo_equip_macro_def_chminmax_chmin{($base:expr,$($cmps:expr),+$(,)*)=>{{let cmp_min=$crate::__cargo_equip::crates::chminmax::min!($($cmps),+);if$base>cmp_min{$base=cmp_min;true}else{false}}};}macro_rules!chmin{($($tt:tt)*)=>(crate::__cargo_equip_macro_def_chminmax_chmin!{$($tt)*})}#[macro_export]macro_rules!__cargo_equip_macro_def_chminmax_chmax{($base:expr,$($cmps:expr),+$(,)*)=>{{let cmp_max=$crate::__cargo_equip::crates::chminmax::max!($($cmps),+);if$base<cmp_max{$base=cmp_max;true}else{false}}};}macro_rules!chmax{($($tt:tt)*)=>(crate::__cargo_equip_macro_def_chminmax_chmax!{$($tt)*})}}
        pub mod mvec {pub use crate::__cargo_equip::macros::mvec::*;#[macro_export]macro_rules!__cargo_equip_macro_def_mvec_mvec{($x:expr;$n:expr)=>{vec![$x;$n]};($x:expr;$n:expr$(;$m:expr)+)=>{vec![mvec![$x$(;$m)*];$n]};}macro_rules!mvec{($($tt:tt)*)=>(crate::__cargo_equip_macro_def_mvec_mvec!{$($tt)*})}}
    }

    pub(crate) mod macros {
        pub mod chminmax {pub use crate::{__cargo_equip_macro_def_chminmax_chmax as chmax,__cargo_equip_macro_def_chminmax_chmin as chmin,__cargo_equip_macro_def_chminmax_max as max,__cargo_equip_macro_def_chminmax_min as min};}
        pub mod mvec {pub use crate::__cargo_equip_macro_def_mvec_mvec as mvec;}
    }

    pub(crate) mod prelude {pub use crate::__cargo_equip::crates::*;}

    mod preludes {
        pub mod chminmax {}
        pub mod mvec {}
    }
}