#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define all(a) a.begin(), a.end()
#define pb push_back
typedef long long ll;
typedef pair<int, int> ii;
const int N = 500 + 5;
const int mod = 1e9 + 7;
void print(){cerr << '\n';} template<typename T1, typename ...T2>
void print(const T1 &a, const T2 &...b){cerr << a << ' ', print(b...);}
bool ok1 = 1;
int n, a[N], b[N];
void fix(int &a)
{
if(a >= mod) a -= mod;
if(a < 0) a += mod;
}
void sub1()
{
int f[n + 1]{1}, res = 0;
for(int i = 1; i <= n; i++)
{
for(int j = 0; j < i; j++)
if(a[j] < a[i]) f[i] += f[j], fix(f[i]);
res += f[i], fix(res);
}
cout << res;
}
bool now = 1, lst = 0;
int dp[2][1000005], sum[1000005], pre[1000005];
void sub2()
{
int res = 0;
dp[0][0] = 1;
sum[0] = 1;
for(int i = 1; i <= n; i++)
{
pre[0] = sum[0];
for(int j = 1; j <= b[i]; j++)
pre[j] = pre[j - 1] + sum[j], fix(pre[j]);
for(int j = a[i]; j <= b[i]; j++)
{
dp[now][j] += pre[j - 1];
fix(dp[now][j]);
res += dp[now][j];
fix(res);
}
for(int j = a[i]; j <= b[j]; j++)
sum[j] += dp[now][j], fix(sum[j]);
swap(now, lst);
}
cout << res;
}
void solve()
{
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> a[i] >> b[i];
if(a[i] != b[i]) ok1 = 0;
}
if(ok1)
sub1();
else
sub2();
}
signed main()
{
// #ifndef ONLINE_JUDGE
// freopen("boat.inp", "r", stdin);
// freopen("boat.out", "w", stdout);
// cin.tie(0) -> sync_with_stdio(0);
// #endif
int t = 1;
// cin >> t;
while(t--) solve();
return 0;
}
