#include <bits/stdc++.h>
using namespace std;
#define int long long
template <typename A, typename B>
string to_string(pair<A, B> p);
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
string to_string(const string& s) {
return '"' + s + '"';
}
string to_string(const char* s) {
return to_string((string) s);
}
string to_string(bool b) {
return (b ? "true" : "false");
}
string to_string(vector<bool> v) {
bool first = true;
string res = "{";
for (int i = 0; i < static_cast<int>(v.size()); i++) {
if (!first) {
res += ", ";
}
first = false;
res += to_string(v[i]);
}
res += "}";
return res;
}
template <size_t N>
string to_string(bitset<N> v) {
string res = "";
for (size_t i = 0; i < N; i++) {
res += static_cast<char>('0' + v[i]);
}
return res;
}
template <typename A>
string to_string(A v) {
bool first = true;
string res = "{";
for (const auto &x : v) {
if (!first) {
res += ", ";
}
first = false;
res += to_string(x);
}
res += "}";
return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << " " << to_string(H);
debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
#define all(a) (a).begin(), (a).end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define reps(i, s, n) for (int i = s; i < (n); ++i)
#define pb push_back
#define sz(a) (int) (a.size())
const int mod = 1e9 + 7;
void solve() {
int n;
cin >> n;
vector<int> a(n), b(n), cs;
rep(i, n) {
cin >> a[i] >> b[i];
cs.pb(a[i]);
cs.pb(b[i]);
}
sort(all(cs));
cs.erase(unique(all(cs)), cs.end());
map<int, int> mp;
vector<int> l, r;
rep(i, sz(cs)) {
if ((i == 0 ? 0 : cs[i - 1]) + 1 <= cs[i] - 1) {
l.pb((i == 0 ? 0 : cs[i - 1]) + 1);
r.pb(cs[i] - 1);
}
mp[cs[i]] = sz(l);
l.pb(cs[i]);
r.pb(cs[i]);
}
rep(i, n) {
a[i] = mp[a[i]];
b[i] = mp[b[i]];
debug(a[i], b[i]);
}
auto add = [&] (int &a, int b) -> void {
(a += b) %= mod;
};
auto mul = [&] (int a, int b) -> int {
return a * b % mod;
};
auto binpow = [&] (int a, int n) -> int {
int res = 1;
while (n) {
if (n % 2) {
res = mul(res, a);
}
a = mul(a, a);
n /= 2;
}
return res;
};
auto inv = [&] (int val) {
return binpow(val, mod - 2);
};
vector<int> f(n + 1), rf(n + 1);
f[0] = rf[0] = 1;
reps(i, 1, n + 1) {
f[i] = mul(f[i - 1], i);
rf[i] = inv(f[i]);
}
auto choose = [&] (int n, int k) {
int res = 1;
reps(i, 1, k + 1) {
res = mul(res, n - k + i);
}
return mul(res, rf[k]);
};
// [i]: 1
// 0 0 0 0 0 1 7 1 3 1 0 0
// [i]: 2
// 0 0 0 1 53 1 35 9 33 13 42 14
// [i]: 3
// 0 1 24 1 1484 55 497 99 0 0 0 0
// [i, x, j, cnt]: 3 6 3 1
// [dp[i][x]]: 399
// [i, x, j, cnt]: 3 6 2 2
// [dp[i][x]]: 441
// [i, x, j, cnt]: 3 6 1 3
// [dp[i][x]]: 497
int segs = sz(l);
vector<vector<int>> C(segs, vector<int> (n + 1));
rep(seg, segs) {
rep(i, n + 1) {
C[seg][i] = choose(r[seg] - l[seg] + 1, i);
}
reps(i, 2, n + 1) {
add(C[seg][i], C[seg][i - 1]);
}
}
int answer = 0;
vector<vector<int>> dp(n, vector<int> (segs));
rep(i, n) {
reps(seg, a[i], b[i] + 1) {
int len = r[seg] - l[seg] + 1;
int cnt = 0;
for (int j = i; j >= 0; j--) {
if (a[j] <= seg && seg <= b[j]) {
cnt++;
if (cnt > len) break;
debug(i, seg, j, cnt);
if (j == 0 || seg == 0) {
add(dp[i][seg], C[seg][cnt]);
} else {
add(dp[i][seg], mul(dp[j - 1][seg - 1], C[seg][cnt]));
}
debug(dp[i][seg]);
}
}
}
debug(i, dp[i]);
reps(j, 1, segs) {
add(dp[i][j], dp[i][j - 1]);
}
add(answer, dp[i][b[i]]);
rep(j, segs) {
add(dp[i][j], (i ? dp[i - 1][j] : 1));
}
}
cout << answer;
// vector<vector<int>> C(sz(segs), vector<int> (n + 1)), Cs(n + 1, vector<int> (n + 1));
// rep(i, sz(segs)) {
// rep(j, min(segs[i].second - segs[i].first + 1, n) + 1) {
// C[i][j] = choose(segs[i].second - segs[i].first + 1, j);
// }
// }
// rep(i, n + 1) {
// rep(j, i + 1) {
// Cs[i][j] = choose(i, j);
// }
// }
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
