#include<bits/stdc++.h>
//#include<chrono>
//#include<random>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;} // greatest common divisor (PGCD)
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);} // least common multiple (PPCM)
int dx[8] = {1, 0, 0, -1, 1, 1, -1, -1};
int dy[8] = {0, 1, -1, 0, 1, -1, -1, 1};
#define endl "\n"
#define ss second
#define ff first
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define vi vector<int>
#define vii vector<pair<int,int>>
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pdd pair<double,double>
#define vdd vector<pdd>
#define speed ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pbds tree<pii, null_type, less<pii>,rb_tree_tag, tree_order_statistics_node_update>
using namespace __gnu_pbds;
using namespace std;
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
////////////////////Only Clear Code//////////////////////////
void usaco_problem(){
freopen("milkvisits.in", "r", stdin);
freopen("milkvisits.out", "w", stdout);
}
void init(){
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif // ONLINE_JUDGE
}
const int mx = 1e6+5;
const int LOG = 22;
const int inf = 1e9;
const ll mod = 1e9+7;
const int sq = 320;
ll d[mx], x[mx];
ll segtree[mx];
void update(int node, int q_low, int q_high, int l, int r, ll v){
if(l >= q_low && r <= q_high){
segtree[node] += v;
segtree[node] %= mod;
return;
}
if(r < q_low || l > q_high){
return;
}
update(2*node, q_low, q_high, l, (l+r)/2, v);
update(2*node+1, q_low, q_high, (l+r)/2 + 1, r, v);
}
int _count(int n){
int c = 0;
while(n > 0){
c+= (n&1);
n/=2;
}
return c;
}
ll value(int node){
ll ans = segtree[node];
for(int j = (node / 2); j > 0;j/=2){
ans += segtree[j];
ans %= mod;
}
return ans;
}
int32_t main(){
speed;
int n;cin >> n;
for(int i = 0; i < n;i++){
cin >> d[i] >> x[i];
x[i] = min(x[i], (long long)n);
}
int n1 = n;
while(_count(n1) != 1){
n1++;
}
update(1, 0, 0, 0, n1-1, 1);
ll ans = 0;
for(int i = 0; i < n;i++){
ll v = value(i+n1) % mod;
update(1, i+1, i+x[i], 0, n1-1, v);
ans += v;
ans %= mod;
}
cout << ans << endl;
}
/*
NEVER GIVE UP!
DOING SMTHNG IS BETTER THAN DOING NTHNG!!!
Your Guide when stuck:
- Continue keyword only after reading the whole input
- Don't use memset with testcases
- Check for corner cases(n=1, n=0)
- Check where you declare n(Be careful of declaring it globally and in main)
*/
