#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = (int)507;
const int mod = (int)1e9 + 7;
int add(int a, int b) {
return (a + b) % mod;
}
int mul(int a, int b) {
return (a * 1LL * b) % mod;
}
int siz = 1;
struct T {
int l, r, val;
T() {
l = r = val = 0;
}
}tree[(int)4e7];
void upd(int pos, int val, int v = 1, int l = 0, int r = 1e9) {
if (l == r) {
tree[v].val = add(tree[v].val, val);
return ;
}
int mid = (l + r) >> 1;
if (pos <= mid) {
if (!tree[v].l)
tree[v].l = ++siz;
upd(pos, val, tree[v].l, l, mid);
} else {
if (!tree[v].r)
tree[v].r = ++siz;
upd(pos, val, tree[v].r, mid + 1, r);
}
tree[v].val = add(tree[tree[v].l].val, tree[tree[v].r].val);
}
int get(int l, int r, int v = 1, int tl = 0, int tr = 1e9) {
if (tl > r || tr < l || v == 0) return 0;
if (l <= tl && tr <= r) return tree[v].val;
int mid = (tl + tr) >> 1;
return add(get(l, r, tree[v].l, tl, mid), get(l, r, tree[v].r, mid + 1, tr));
}
int n;
int a[N], b[N];
main() {
scanf("%d", &n);
for (int i = 1; i <= n; i++) {
scanf("%d %d", &a[i], &b[i]);
}
upd(0, 1);
for (int i = 1; i <= n; i++) {
for (int j = b[i]; j >= a[i]; j--) {
upd(j, get(0, j - 1));
}
}
cout << add(get(0, 1e9), mod - 1);
}
