#include <bits/stdc++.h>
#define pii pair<int,int>
#define fi first
#define int long long
#define se second
#define ios ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define op freopen
#define TXT "test"
#define freo if(fopen(TXT".inp","r")){op(TXT".inp","r",stdin);op(TXT".out","w",stdout);}

using namespace std;
int n,m,a[1000006*2],b[1000006*2];
int res=0;

main()
{
    ios;
    freo;
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    for(int i=1;i<=m;i++)
    {
        cin>>b[i];
    }
    sort(a+1,a+1+n);
    sort(b+1,b+1+m);
    int c=1,i,res=0;
    for(i=1;i<=m&&c<=n;i++)
    {
        while(c<=n&&a[c]<b[i])
        {
            c++;
        }
        if(a[c]>=b[i])
        {
            res+=a[c];
            c++;
        }
    }
    if(i>m)
    {
        cout<<res;
    }
    else
    {
        cout<<-1;
    }
}