#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
#define REP(i,n) for(ll i=0;i<(n);i++)
#define ALL(v) v.begin(),v.end()
template<typename T> bool chmax(T &x, const T &y) {return (x<y)?(x=y,true):false;};
template<typename T> bool chmin(T &x, const T &y) {return (x>y)?(x=y,true):false;};
constexpr ll MOD=1000000007;
constexpr ll INF=2e18;

struct Unionfind{
   vector<int> par, siz;
   Unionfind(int N):par(N), siz(N,1){
       for(int i=0;i<N;i++) par[i]=i;
   }
   int root(int x){
       while(par[x]!=x) x=par[x]=par[par[x]];
       return x;
   }
   void unite(int x, int y){
       x=root(x); y=root(y);
       if(x==y) return;
       if(siz[x]<siz[y]) swap(x,y);
       siz[x]+=siz[y];
       par[y]=x;
   }
   bool same(int x, int y){
       return root(x)==root(y);
   }
   int size(int x){
       return siz[root(x)];
   }
};

int main(){
    int n, m; cin >> n >> m;
    VI a(n), b(m);
    REP(i,n) cin >> a[i];
    REP(i,m) cin >> b[i];
    vector<P> p;
    REP(i,n) p.push_back({a[i],0});
    REP(i,m) p.push_back({b[i],1});
    sort(ALL(p));
    vector<P> q;
    REP(i,n+m-1){
        if(!(p[i].second==0&&p[i+1].second==0)){
            q.push_back({p[i+1].first-p[i].first,i});
        }
    }
    sort(ALL(q));
    Unionfind uf(n+m);
    VI f(n+m,0);
    REP(i,n+m){
        if(p[i].second==0)
            f[i]=1;
    }
    ll ans=0;
    for(auto [d,x]:q){
        int r1=uf.root(x), r2=uf.root(x+1);
        if(f[r1]&&f[r2])
            continue;
        else if(f[r1]||f[r2]){
            f[r1]=1;
            f[r2]=1;
            uf.unite(r1,r2);
            ans+=d;
        }
        else{
            uf.unite(r1,r2);
            ans+=d;
        }
    }
    cout << ans << endl;
    return 0;
}