#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);
for(ll i = 1; i <= n; i++){
ll last = INF;
for(ll j = i+1; j <= n; j++){
if(!inside(a[j].first,a[j].second,a[i].first,a[i].second)){
last = j-1;
break;
}
}
if(last == INF) last = n;
left[i] = last;
}
vector<ll> dp(n+5);
dp[1] = 1;
for(ll i = 1; i <= n; i++){
dp[i] = dp[i-1]+1;
bool allinside = true;
for(ll j = i-1; j >= 1; j--){
if(left[j] >= i){
dp[i] = min(dp[i],dp[j]);
}
if(inside(a[j].first,a[j].second,a[i].first,a[i].second) && allinside){
dp[i] = min(dp[i],dp[j-1]+1);
}
else allinside = false;
}
}
cout << dp[n];
}
int main(){
fast;
ll tc = 1;
// cin >> tc;
while(tc--) solve();
return 0;
}
