Description：

Solution：

Code：

#include<algorithm>

#include<iostream>

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<cctype>

#include<cstring>

using namespace std;

int n,m;

#define MAXN 50010

int p[MAXN];

int v[MAXN];

#define MOD 1000000007

struct node

{

	int lc,rc;

	int sum,tot;

	node(){sum = 0;}

}t[MAXN * 250];

int ptr = 0;

int newnode(){return ++ptr;}

#define mid ((l + r) >> 1)

void insert(int &rt,int p,int k,int c,int l,int r)

{

	if(rt == 0)rt = newnode();

	t[rt].sum = (t[rt].sum + k) % MOD;t[rt].tot += c;

	if(l == r)return;

	if(p <= mid)insert(t[rt].lc,p,k,c,l,mid);

	else insert(t[rt].rc,p,k,c,mid + 1,r);

	return;

}

int query_sum(int rt,int L,int R,int l,int r)

{

	if(rt == 0)return 0;

	if(L <= l && r <= R)return t[rt].sum;

	int res = 0;

	if(L <= mid)res = (res + query_sum(t[rt].lc,L,R,l,mid)) % MOD;

	if(R > mid)res = (res + query_sum(t[rt].rc,L,R,mid + 1,r)) % MOD;

	return res;

}

int query_tot(int rt,int L,int R,int l,int r)

{

	if(rt == 0)return 0;

	if(L <= l && r <= R)return t[rt].tot;

	int res = 0;

	if(L <= mid)res += query_tot(t[rt].lc,L,R,l,mid);

	if(R > mid)res += query_tot(t[rt].rc,L,R,mid + 1,r);

	return res;

}

int root[MAXN];

int ans = 0;

int lowbit(int x){return x & (-x);}

void add(int k,int p,int v)

{

	for(int i = k;i <= n;i += lowbit(i))insert(root[i],p,v,1,1,n);

	return;

}

void del(int k,int p,int v)

{

	for(int i = k;i <= n;i += lowbit(i))insert(root[i],p,-v,-1,1,n);

	return;

}

int query1(int l1,int r1,int l2,int r2)

{

	if(l1 > r1 || l2 > r2)return 0;

	int res = 0;

	for(int i = r1;i >= 1;i -= lowbit(i))res = (res + query_sum(root[i],l2,r2,1,n)) % MOD;

	for(int i = l1 - 1;i >= 1;i -= lowbit(i))res = (res - query_sum(root[i],l2,r2,1,n) + MOD) % MOD;

	return res;

}

int query2(int l1,int r1,int l2,int r2)

{

	if(l1 > r1 || l2 > r2)return 0;

	int res = 0;

	for(int i = r1;i >= 1;i -= lowbit(i))res += query_tot(root[i],l2,r2,1,n);

	for(int i = l1 - 1;i >= 1;i -= lowbit(i))res -= query_tot(root[i],l2,r2,1,n);

	return res;

}

int main()

{

	scanf("%d%d",&n,&m);

	for(int i = 1;i <= n;++i)scanf("%d%lld",&p[i],&v[i]);

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

	{

		ans = (ans + query1(1,i - 1,p[i] + 1,n)) % MOD;

		ans = (ans + 1ll * query2(1,i - 1,p[i] + 1,n) * v[i] % MOD) % MOD;

		ans = (ans + query1(i + 1,n,1,p[i] - 1)) % MOD;

		ans = (ans + 1ll * query2(i + 1,n,1,p[i] - 1) * v[i] % MOD) % MOD;

		add(i,p[i],v[i]);

	}

	int x,y;

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

	{

		scanf("%d%d",&x,&y);

		del(x,p[x],v[x]);

		ans = (ans - query1(1,x - 1,p[x] + 1,n) + MOD) % MOD;

		ans = (ans - 1ll * query2(1,x - 1,p[x] + 1,n) * v[x] % MOD + MOD) % MOD;

		ans = (ans - query1(x + 1,n,1,p[x] - 1) + MOD) % MOD;

		ans = (ans - 1ll * query2(x + 1,n,1,p[x] - 1) * v[x] % MOD + MOD) % MOD;

		del(y,p[y],v[y]);

		ans = (ans - query1(1,y - 1,p[y] + 1,n) + MOD) % MOD;

		ans = (ans - 1ll * query2(1,y - 1,p[y] + 1,n) * v[y] % MOD + MOD) % MOD;

		ans = (ans - query1(y + 1,n,1,p[y] - 1) + MOD) % MOD;

		ans = (ans - 1ll * query2(y + 1,n,1,p[y] - 1) * v[y] % MOD + MOD) % MOD;

		swap(p[x],p[y]);swap(v[x],v[y]);

		add(x,p[x],v[x]);

		ans = (ans + query1(1,x - 1,p[x] + 1,n)) % MOD;

		ans = (ans + 1ll * query2(1,x - 1,p[x] + 1,n) * v[x] % MOD) % MOD;

		ans = (ans + query1(x + 1,n,1,p[x] - 1)) % MOD;

		ans = (ans + 1ll * query2(x + 1,n,1,p[x] - 1) * v[x] % MOD) % MOD;

		add(y,p[y],v[y]);

		ans = (ans + query1(1,y - 1,p[y] + 1,n)) % MOD;

		ans = (ans + 1ll * query2(1,y - 1,p[y] + 1,n) * v[y] % MOD) % MOD;

		ans = (ans + query1(y + 1,n,1,p[y] - 1)) % MOD;

		ans = (ans + 1ll * query2(y + 1,n,1,p[y] - 1) * v[y] % MOD) % MOD;

		printf("%lld\n",ans);

	}

	return 0;

}