/*
Author: Nguyen Chi Thanh - High School for the Gifted - VNU.HCM (i2528)
*/
#include <bits/stdc++.h>
using namespace std;
/* START OF TEMPALTE */
// #define int long long
#define ll long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) (1ll << (x))
#define SZ(a) ((int32_t)a.size())
#define debug(a, l, r) {for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';}
template<class X, class Y>
bool minimize(X &x, const Y &y) {
if (x > y) {
x = y;
return true;
} else return false;
}
template<class X, class Y>
bool maximize(X &x, const Y &y) {
if (x < y) {
x = y;
return true;
} else return false;
}
/* END OF TEMPALTE */
const int MAXN = 2e5 + 5;
const int INF = (int)1e9 + 5;
int n, l[MAXN], r[MAXN], dp[MAXN];
void init() {
cin >> n;
for (int i = 1; i <= n; ++i)
cin >> l[i] >> r[i];
}
void solve() {
fill(dp, dp + n + 1, -INF);
dp[0] = 0;
for (int i = 1; i <= n; i++) {
int pre = i - l[i] - 1;
for (int j = 0; j <= pre; j++) {
if (j == 0 || j + r[j] < i) {
dp[i] = max(dp[i], dp[j] + 1);
}
}
}
cout << *max_element(dp, dp + n + 1);
}
signed main() {
#ifdef NCTHANH
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
init();
solve();
return 0;
}
