#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int MAXN = 5e5 + 5;
const int MAXM = 10 + 5;
const ll linf = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;

inline void add_mod(int &a,int b){ a+=b; if(a>=mod) a-=mod;}
inline int mod_add(int a,int b){ return a+b>=mod? a+b-mod: a+b;}

inline ll pw(ll a,ll b)
{
	ll res = 1;
	while(b)
	{
		if(b&1) res=res*a%mod;
		a=a*a%mod; b>>=1;
	}
	return res;
}

inline vector<int> mul(const vector<int> &A,const vector<int> &B)
{
	if(!A.size() || !B.size()) return {};
	vector<int> res((int)A.size() + (int)B.size() - 1);
	for(int i=0; i<(int)A.size(); ++i)
		for(int j=0; j<(int)B.size(); ++j)
			res[i+j] = (res[i+j] + (ll)A[i] * B[j]) %mod;
	return res;
}

inline int calc_poly(const vector<int> &A,int x)
{
	int res = 0;
	for(int i=0, cur=1; i<(int)A.size(); ++i)
		res = (res + (ll)A[i] * cur) %mod,
		cur = (ll)cur * x %mod;
	return res;
}

inline int interpolation(const vector<int> &ys,ll x)
{
	x %= mod;
	int n = (int)ys.size(), res = 0;
	for(int i=0; i<n; ++i)
	{
		int cur = 1;
		for(int j=0; j<n; ++j)
			if(j != i) cur = (ll)cur * (i-j) %mod;
		cur = pw(cur, mod-2) * ys[i] %mod;
		for(int j=0; j<n; ++j)
			if(j != i) cur = (ll)cur * (x-j) %mod;
		res = (res + cur) %mod;
	}
	add_mod(res, mod);
	return res;
}

int a[MAXM];
int c[MAXN * 3], d[MAXN * 3];
int mn[MAXN * 3][MAXM], mx[MAXN * 3][MAXM];
int len[MAXN * 3][MAXM];

int main(void)
{
	int n,m;
	scanf("%d%d",&n,&m);
	for(int i=1; i<=m; ++i) scanf("%d",&a[i]);
	for(int i=1; i<=n; ++i) scanf("%d%d",&c[i],&d[i]);
	
	ll lim = linf;
	for(int i=1; i<=n; ++i)
		c[i+n] = c[i+2*n] = c[i],
		d[i+n] = d[i+2*n] = d[i];
	
	vector<int> cx(m+1);
	for(int i=1; i<=3*n; ++i)
	{
		cx[c[i]] += d[i];
		for(int j=1; j<=m; ++j)
		{
			mn[i][j] = min(mn[i-1][j], cx[j]);
			mx[i][j] = max(mx[i-1][j], cx[j]);
			len[i][j] = a[j] - (mx[i][j] - mn[i][j] + 1) + 1;
			if(len[i][j] <= 0) lim = min(lim, (ll)i);
		}
	}
	
	auto getsiz = [&] (int i,ll k)
	{
		ll cmn = k / (3*n) * cx[i] + mn[k % (3*n)][i];
		ll cmx = k / (3*n) * cx[i] + mx[k % (3*n)][i];
		cmn = min(cmn, (ll)mn[n][i]);
		cmx = max(cmx, (ll)mx[n][i]);
		return cmx - cmn + 1;
	};
	
	if(lim == linf)
	{
		for(int i=1; i<=m; ++i) if(cx[i])
		{
			ll l = 3 * n, r = (ll)a[i] * n + 5;
			if(getsiz(i, r) <= a[i]) continue;
			while(l<r)
			{
				ll mid = (l+r)>>1;
				if(getsiz(i, mid) <= a[i]) l = mid+1;
				else r = mid;
			}
			lim = min(lim, l);
		}
	}
	if(lim == linf)
	{
		printf("-1");
		return 0;
	}
	
	int ans = 0;
	for(int i=1; i<=n; ++i) if(i <= lim)
	{	
		auto get = [&] (int a0,int a1)
		{
			add_mod(a0 %= mod, mod); add_mod(a1 %= mod, mod);
			int _k = mod_add(a1 - a0, mod);
			return vector<int>{a0, _k};
		};
		
		ll t = (lim - i) / n + 1;
		
		int fir = 1;
		for(int j=1; j<=m; ++j)
			fir = (ll)fir * len[i][j] %mod;
		add_mod(ans, fir);
		if(t == 1) continue;
		
		vector<int> p = {1};
		for(int j=1; j<=m; ++j)
			p = mul(p, get(len[i+n][j], len[i+2*n][j]));
		
		int sum = 0;
		vector<int> ys(m+2);
		for(int j=0; j<m+2; ++j)
		{
			add_mod(sum, calc_poly(p, j));
			ys[j] = sum;
		}
		
		add_mod(ans, interpolation(ys, t - 2));
	}
	
	int tot = 1;
	for(int i=1; i<=m; ++i) tot = (ll)tot * a[i] %mod;
	ans = (ans + tot) %mod;
	
	printf("%d",ans);
	return 0;
}