#include<bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define fi first
#define se second
using namespace std;
int const mod=1e9+7;
map<int,int> ind;
vector<int> val;
vector<int> fen(1010,0);
void upd(int idx,int val)
{
idx+=2;
for(int i=idx;i<1010;i+=i&-i)fen[i]+=val,fen[i]%=mod;
}
int qr(int idx)
{
idx+=2;
int ret=0;
for(int i=idx;i>0;i-=i&-i)ret+=fen[i],ret%=mod;
return ret;
}
int pow(int a,int b)
{
if(b==0)return 1;
if(b==1)return a;
int ret=pow(a,b/2);
if(b%2==0)return (ret*ret)%mod;
else return (((ret*ret)%mod)*a)%mod;
}
map<int,int> inverse;
int inv(int a)
{
if(inverse[a]!=0)return inverse[a];
inverse[a]=pow(a,mod-2);
return inverse[a];
}
map<pii,int> chos;
int choose(int a,int b)
{
if(b>a)return 0;
int ret=1;
if(chos[{a,b}]!=0)return chos[{a,b}];
for(int i=b+1;i<=a;i++)
{
ret*=i;
ret%=mod;
}
for(int i=2;i<=a-b;i++)
{
ret*=inv(i);
ret%=mod;
}
chos[{a,b}]=ret;
return ret;
}
signed main()
{
int n;
cin>>n;
vector<pii> info;
set<int> temp;
for(int i=0;i<n;i++)
{
int a,b;
cin>>a>>b;
temp.insert(a);
temp.insert(b+1);
info.push_back({a,b+1});
}
for(auto it:temp)
{
val.push_back(it);
ind[it]=val.size()-1;
//cout<<it<<" "<<ind[it]<<endl;
}
vector<vector<int>> pre(510,vector<int>(1010,-2));
vector<int> latest(1010,-1);
upd(-1,1);
vector<vector<int>> dp(510,vector<int>(1010,0));
for(int i=0;i<n;i++)
{
//cout<<endl<<i<<":";
for(int j=ind[info[i].se]-1;j>=ind[info[i].fi];j--)
{
//cout<<j<<" ";
int bef=latest[j];
pre[i][j]=latest[j];
latest[j]=i;
int a=qr(j),b=(val[j+1]-val[j]),c=0;
dp[i][j]=a;
int ans=a*b;
ans%=mod;
int k=2;
//cout<<i<<" "<<j<<" "<<ans<<" ";
while(bef!=-1)
{
ans+=dp[bef][j]*choose(b+k-2,k);
ans%=mod;
bef=pre[bef][j];
k++;
//cout<<endl<<bef<<" "<<ans<<" ";
}
// cout<<endl;
upd(j+1,ans);
}
}
cout<<(qr(1007)+mod-1)%mod;
return 0;
}
