#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define pb push_back
#define ff first
#define ss second
const int mod = 1e9 + 7;
vector<int> operator * (vector<int> a, vector<int> b){
vector<int> f(a.size() + b.size() - 1);
for (int i = 0; i < a.size(); i++){
for (int j = 0; j < b.size(); j++){
f[i + j] = (f[i + j] + 1LL * a[i] * b[j]) % mod;
}
}
return f;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
auto bin_pow = [&](int x, int y){
int out = x, pr = x; y--;
while (y > 0){
if (y & 1){
out = (1LL * out * pr) % mod;
}
pr = (1LL * pr * pr) % mod;
y >>= 1;
}
return out;
};
auto inv = [&](int x){
if (x < 0) x += mod;
return bin_pow(x, mod - 2);
};
int n; cin>>n;
vector<int> pw(n + 3, 1), P[n + 3], T[n + 3], d;
for (int i = 1; i <= n + 2; i++){
T[i] = {0, inv(i)};
}
for (int x = 1; x <= n + 2; x++){
for (int j = 1; j <= n + 2; j++){
if (j != x){
int v = (-1LL * x * inv(j - x)) % mod + mod;
d = {v, inv(j - x)};
T[j] = T[j] * d;
}
}
P[x - 1].resize(x + 1);
int X = 0;
for (int i = 1; i <= x; i++){
X = (X + pw[i]) % mod;
for (int j = 0; j < T[i].size(); j++){
P[x - 1][j] = (P[x - 1][j] + 1LL * T[i][j] * X) % mod;
}
}
for (int j = 1; j <= n + 2; j++){
pw[j] = (1LL * pw[j] * j) % mod;
}
}
set<pair<int, pair<int, vector<int>>>> st;
st.insert({1, {1e9, {0}}});
auto split = [&](int x){
auto it = st.lower_bound({x + 1, {}});
if (it != st.begin()){
it--;
if ((*it).ss.ff != x){
int l = (*it).ff, r = (*it).ss.ff;
vector<int> f = (*it).ss.ss;
st.erase(it);
st.insert({l, {x, f}});
st.insert({x + 1, {r, f}});
}
}
};
auto F = [&](int i, int j){
int out = 0, X = 1;
for (int t = 0; t < P[i].size(); t++){
out = (out + 1LL * P[i][t] * X) % mod;
X = (1LL * X * j) % mod;
}
return out;
};
for (int tt = 1; tt <= n; tt++){
int l, r; cin>>l>>r;
split(l - 1); split(r);
int X = 0;
auto it = st.begin();
while ((*it).ff < l){
int a = (*it).ff, b = (*it).ss.ff;
vector<int> f = (*it).ss.ss;
for (int i = 0; i < f.size(); i++){
X = (X + 1LL * f[i] * (F(i, b) - F(i, a - 1))) % mod;
}
it++;
}
while (it != st.end() && (*it).ff <= r){
int a = (*it).ff, b = (*it).ss.ff;
vector<int> f = (*it).ss.ss, t((int) f.size() + 2); t[0] = (X + 1) % mod;
for (int i = 0; i < f.size(); i++){
for (int s = 0; s < P[i].size(); s++){
t[s] = (t[s] + 1LL * f[i] * P[i][s]) % mod;
}
t[0] = (t[0] - 1LL * f[i] * F(i, a - 1)) % mod;
X = (X + 1LL * f[i] * (F(i, b) - F(i, a - 1))) % mod;
}
while (t.size() > 1 && !t.back()) t.pop_back();
st.erase(it);
st.insert({a, {b, t}});
it = st.find({a, {b, t}}); it++;
}
}
auto it = st.begin();
int out = 0;
while (it != st.end()){
int a = (*it).ff, b = (*it).ss.ff;
vector<int> f = (*it).ss.ss;
for (int i = 0; i < f.size(); i++){
out = (out + 1LL * f[i] * (F(i, b) - F(i, a - 1))) % mod;
}
it++;
}
if (out < 0) out += mod;
cout<<out<<"\n";
}
