// Slower C++ solution:
#include<bits/stdc++.h>

#define ll long long

#define max(a,b) ((a)>(b)?(a):(b))

#define min(a,b) ((a)<(b)?(a):(b))

#define swap(x,y) (x^=y^=x^=y)

inline int read()

{

	int x=0,f=1;char ch=getchar();

	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}

	while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+ch-'0';ch=getchar();}

	return x*f;

}

#define MN 100005

#define mod 1000000007

int ans,x[MN],y[MN];

int cnt,a[MN],b[MN],B[MN],id[MN];

inline bool cmp(const int&o,const int&oo){return a[o]==a[oo]?b[o]<b[oo]:a[o]<a[oo];}

int t[MN],s[MN];

void C(int x,int v){for(;x<MN;x+=(x&-x))(t[x]+=v)%=mod;}

int G(int x){int r=0;for(;x;x-=(x&-x))(r+=t[x])%=mod;return r;}

int main()

{

	register int i,j,n,m;

	n=read(),m=read();

	for(i=1;i<=n;++i) x[i]=read();

	for(j=1;j<=m;++j) y[j]=read();

	std::sort(x+1,x+n+1);std::sort(y+1,y+m+1);

	for(i=1;i<=n;++i)

	{

		int p=std::lower_bound(y,y+m+1,x[i])-y;

		if(p<=1||p>m||x[i]==y[p]) continue;

		a[++cnt]=x[i]-y[p-1];B[cnt]=b[cnt]=y[p]-x[i];id[cnt]=cnt;

	}

	std::sort(B+1,B+cnt+1);

	int Bcnt=std::unique(B+1,B+cnt+1)-B-1;

	for(i=1;i<=cnt;i++) b[i]=std::lower_bound(B+1,B+Bcnt+1,b[i])-B;

	std::sort(id+1,id+cnt+1,cmp);

	for(i=1,j=1;i<=cnt;++i)

	{

		if(a[id[i]]==a[id[i-1]]&&b[id[i]]==b[id[i-1]]) continue;

		for(;a[id[j]]<a[id[i]];++j) if(a[id[j]]!=a[id[j-1]]||b[id[j]]!=b[id[j-1]]) C(b[id[j]],s[j]%mod);

		s[i]=1+G(b[id[i]]-1);

		(ans+=(s[i]%mod))%=mod;

	}

	printf("%d\n",ans+1);

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 5.190209134816919x):
#include <cstdio>

#include <algorithm>

#include <vector>

#define file(x) freopen(#x".in", "r", stdin), freopen(#x".out", "w", stdout)



inline int read()

{

	int data = 0, w = 1; char ch = getchar();

	while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();

	if (ch == '-') w = -1, ch = getchar();

	while (ch >= '0' && ch <= '9') data = data * 10 + (ch ^ 48), ch = getchar();

	return data * w;

}



const int maxn(100010), Mod(1e9 + 7);

int n, m, A[maxn], B[maxn], S[maxn], c[maxn], f[maxn], tot;

struct node { int x, y; } P[maxn];

inline bool operator == (const node &lhs, const node &rhs)

	{ return lhs.x == rhs.x && lhs.y == rhs.y; }

void Add(int x, int v) { for (; x <= tot; x += x & -x) c[x] = (c[x] + v) % Mod; }

int Sum(int x) { int ans = 0; for (; x; x -= x & -x) ans = (ans + c[x]) % Mod; return ans; }



int main()

{

	n = read(), m = read();

	for (int i = 1; i <= n; i++) A[i] = read();

	for (int i = 1; i <= m; i++) B[i] = read();

	P[tot = 1] = (node) {0, 0};

	for (int i = 1, j; i <= n; i++)

	{

		j = std::upper_bound(B + 1, B + m + 1, A[i]) - B;

		if (j > 1 && j <= m) P[++tot] = (node) {A[i] - B[j - 1], B[j] - A[i]};

	}

	P[n = ++tot] = (node) {(int)1e9, (int)1e9}, tot = 0;

	for (int i = 1; i <= n; i++) S[i] = P[i].y;

	std::sort(S + 1, S + n + 1), tot = std::unique(S + 1, S + n + 1) - S - 1;

	for (int i = 1; i <= n; i++)

		P[i].y = std::lower_bound(S + 1, S + tot + 1, P[i].y) - S;

	std::sort(P + 1, P + n + 1, [] (const node &lhs, const node &rhs)

			{ return lhs.x != rhs.x ? lhs.x < rhs.x : lhs.y < rhs.y; });

	n = std::unique(P + 1, P + n + 1) - P - 1;

	Add(P[1].y, 1);

	for (int i = 2, j; i <= n; i = j)

	{

		for (j = i; j <= n && P[j].x == P[i].x; j++);

		for (int k = i; k < j; k++) f[k] = Sum(P[k].y - 1);

		for (int k = i; k < j; k++) Add(P[k].y, f[k]);

	}

	printf("%d\n", f[n]);

	return 0;

}

//