#include<bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define ll long long int
const ll N = 100+5 , INF = 1e18 , MOD = 1e9+7;
bool inside(ll x1 , ll y1 , ll x2 , ll y2){
return (abs(x2-x1) <= (y2-y1));
}
void solve(){
ll n;
cin >> n;
vector<pair<ll,ll>> a(n+5);
for(ll i = 1; i <= n; i++) cin >> a[i].first >> a[i].second;
vector<ll> left(n+5) , right(n+5);
for(ll i = 1; i <= n; i++){
for(ll j = i; j >= 1; j--){
if(inside(a[j].first,a[j].second,a[i].first,a[i].second)) left[i] = j;
else break;
}
}
for(ll i = 1; i <= n; i++){
for(ll j = i; j <= n; j++){
if(inside(a[j].first,a[j].second,a[i].first,a[i].second)) right[i] = j;
else break;
}
}
vector<ll> dp(n+5,INF);
dp[0] = 0;
for(ll i = 1; i <= n; i++){
dp[i] = min(dp[i],dp[left[i]-1]+1);
dp[right[i]] = min(dp[right[i]],dp[left[i]-1]+1);
}
cout << dp[n];
}
int main(){
fast;
ll tc = 1;
// cin >> tc;
while(tc--) solve();
return 0;
}
