#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define REPD(i, a) for (int i = (a) - 1; i >= 0; --i)
#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
/*
Phu Trong from Nguyen Tat Thanh High School for gifted student
*/
template <class X, class Y>
bool minimize(X &x, const Y &y){
X eps = 1e-9;
if (x > y + eps) {x = y; return 1;}
return 0;
}
template <class X, class Y>
bool maximize(X &x, const Y &y){
X eps = 1e-9;
if (x + eps < y) {x = y; return 1;}
return 0;
}
#define MAX 100005
#define BLOCK_SIZE 333
int numTrain;
pair<int, int> A[MAX]; //(time between each stop point, num stop point)
int dp[MAX];
void add(int &x, int y){
x += y;
if (x >= Mod) x %= Mod;
while(x < 0) x += Mod;
}
int pref[MAX][BLOCK_SIZE + 5];
void process(void){
cin >> numTrain;
for (int i = 1; i <= numTrain; ++i) cin >> A[i].first >> A[i].second;
dp[1] = 1;
int ans = 0;
for (int i = 1; i <= numTrain; ++i){
for (int v = 1; v <= BLOCK_SIZE; ++v){
if(i >= v) add(pref[i][v], pref[i - v][v]);
add(dp[i], pref[i][v]);
}
if (A[i].first >= BLOCK_SIZE){
int x = A[i].second;
for (int v = i + A[i].first; v <= numTrain && x > 0; v += A[i].first, x--){
add(dp[v], dp[i]);
}
}
else{
add(pref[i][A[i].first], dp[i]);
int fin = min(numTrain + 1, i + (A[i].first * (A[i].second + 1)));
add(pref[fin][A[i].first], -dp[i]);
}
add(ans, dp[i]);
}
cout << ans;
}
signed main(){
#define name "Whisper"
cin.tie(nullptr) -> sync_with_stdio(false);
//freopen(name".inp", "r", stdin);
//freopen(name".out", "w", stdout);
process();
return (0 ^ 0);
}
