#include<bits/stdc++.h>
using namespace std;
inline int read()
{
    int x=0;char c=getchar();
    while(!isdigit(c)) c=getchar();
    while(isdigit(c)) x=x*10+(c^48),c=getchar();
    return x;
}
const int N=5e5+3;
int n,A,B,a[N],b[N],id[N<<2];
int tot=-1,h[N*3],cnt,S,T;
struct edge{int v,w,f,nxt;}e[N<<6];
inline void add(int u,int v,int w,int f) {e[++tot]={v,w,f,h[u]},h[u]=tot;}
inline void lnk(int u,int v,int w,int f) {add(u,v,w,f),add(v,u,0,-f);}
#define mid ((l+r)>>1)
#define ls (x<<1)
#define rs (x<<1|1)
inline void bil(int x=1,int l=1,int r=n)
{
    id[x]=++cnt;
    if(l==r) return lnk(id[x],T,1,0);
    bil(ls,l,mid),lnk(id[x],id[ls],mid-l+1,0);
    bil(rs,mid+1,r),lnk(id[x],id[rs],r-mid,0);
}
inline void Lnk(int k,int L,int R,int f,int x=1,int l=1,int r=n)
{
    if(L<=l&&r<=R) return lnk(k,id[x],1,f);
    if(L<=mid) Lnk(k,L,R,f,ls,l,mid);
    if(R>mid) Lnk(k,L,R,f,rs,mid+1,r);
}
int mxw,mxf,d[N*3],cur[N*3];
bool vis[N*3];
deque<int> q;
inline bool chx(int &x,int y) {return x<y?(x=y,1):0;}
inline bool spfa()
{
    for(int i=1;i<=cnt;++i) d[i]=-N,cur[i]=h[i];
    d[S]=0,q.push_front(S);
    while(!q.empty()) 
    {
        int u=q.front();q.pop_front();
        vis[u]=0;
        for(int i=h[u],v;~i;i=e[i].nxt)
        {
            v=e[i].v;
            if(!e[i].w||!chx(d[v],d[u]+e[i].f)||vis[v]) continue;
            vis[v]=1;
            if(!q.empty()&&d[v]>d[q.front()]) q.push_front(v);
            else q.push_back(v); 
        }
    }
    return d[T]>-N;
}
inline int dfs(int u=S,int flow=N)
{
    if(u==T) return (mxf+=d[T]*flow),flow;
    int rmn=flow;
    vis[u]=1;
    for(int i=cur[u],v;~i&&rmn;i=e[i].nxt) 
    {
        cur[u]=i,v=e[i].v;
        if(!vis[v]&&e[i].w&&d[u]+e[i].f==d[v])
        {
            int c=dfs(v,min(rmn,e[i].w));
            rmn-=c,e[i].w-=c,e[i^1].w+=c;
        }
    }
    vis[u]=0;
    return flow-rmn;
}
int main()
{
    memset(h,-1,sizeof(h));
    n=read(),A=read(),B=read();
    for(int i=1;i<=n;++i) a[i]=read();
    for(int i=1;i<=n;++i) b[i]=read();
    sort(a+1,a+n+1),sort(b+1,b+n+1);
    S=++cnt,T=++cnt,bil();
    for(int i=1,x=1,y=1,z=1;i<=n;++i)
    {
        while(x<=n&&b[x]<a[i]) ++x;
        while(y<=n&&b[y]<=a[i]+A-B) ++y;
        while(z<=n&&b[z]<=a[i]+A) ++z;
        lnk(S,++cnt,1,0);
        if(x<y) Lnk(cnt,x,y-1,1);
        if(y<z) Lnk(cnt,y,z-1,0); 
    } 
    while(spfa()) for(int x;(x=dfs());mxw+=x);
    if(mxw<n) puts("-1");
    else printf("%d\n",mxf);
    return 0;
}