#include<iostream>
#include<stdio.h>
#include<vector>
using namespace std;
typedef long long int lld;
#define MOD 1000000007
struct node{
int l,r;
lld val;
node *left,*right;
};
void build(node *n,int l, int r){
n->val=0;
n->l=l;
n->r=r;
}
void extend(node *n){
if(n->left!=NULL)return;
int mid=(n->l+n->r)/2;
n->left=new node();
n->right=new node();
build(n->left,n->l,mid);
build(n->right,mid+1,n->r);
}
void update(int pos, lld val,node *n){
if(pos<n->l || pos>n->r)return;
n->val+=val;
n->val%=MOD;
if(n->l!=n->r){
extend(n);
update(pos,val,n->left);
update(pos,val,n->right);
}
}
lld prefixo(int index, node *n){
if(n->r<=index)return n->val;
if(n->l>index || n->val==0) return 0;
lld ans=prefixo(index,n->left);
ans+=prefixo(index,n->right);
return ans%MOD;
}
int main(){
int n;
cin>>n;
pair<lld,lld> arr[n];
for(int i=0;i<n;i++)cin>>arr[i].first>>arr[i].second;
vector<lld> DP[n];
lld responde=0;
node *segtree=new node();
build(segtree,1,1000000000);
for(int i=0;i<n;i++){
for(int j=arr[i].first;j<=arr[i].second;j++){
DP[i].push_back((prefixo(j-1,segtree)+1)%MOD);
}
for(int j=arr[i].first;j<=arr[i].second;j++){
update(j,DP[i][j-arr[i].first],segtree);
}
}
/*for(int i=0;i<n;i++){
for(int j=arr[i].first;j<=arr[i].second;j++){
cout<<DP[i][j-arr[i].first]<<" ";
}cout<<endl;
}*/
for(int i=0;i<n;i++){
for(int j=arr[i].first;j<=arr[i].second;j++){
responde+=DP[i][j-arr[i].first];
responde%=MOD;
}
}
cout<<responde<<endl;
return 0;
}
