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#include <bits/stdc++.h>
 
using namespace std;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef long long LL;
typedef pair<int,int> PI; 
typedef pair<LL,LL> PLL;
typedef unsigned long long ULL;
typedef pair<double,double> PD;
 
#define FOR(x, b, e) for(int x = b; x<= (e); x++)
#define FORD(x, b, e) for(int x = b; x>= (e); x--)
#define REP(x, n) for(int x = 0; x<(n); ++x)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
 
#define PB push_back
#define IN insert
#define ST first
#define ND second
#define INF 2000000011
#define MOD 1000000007

#define MAXS 300010

int n;
PI arr[MAXS];
VI graf[MAXS];

int odw[MAXS];

void dfs(int v){
    odw[v]=1;
    for(auto x:graf[v]){
        if(!odw[x])
            dfs(x);
    }
}


int detonate(int mask){
    REP(i,n){
        if((1<<i&mask)&&(odw[i]==0))
            dfs(i);
    }
    int m1=0;
    REP(i,n){
        if(odw[i])
            m1|=1<<i;
        odw[i]=0;
    }
    
    return m1;
}


int main(){

    ios::sync_with_stdio(0);cin.tie(0);

    cin>>n;
    REP(i,n)
        cin>>arr[i].ST>>arr[i].ND;
    
    REP(i,n){
        FOR(j,i+1,n-1){
            if(arr[i].ST+arr[i].ND>=arr[j].ST)
                graf[i].PB(j);
            else
                break;
        }
        FORD(j,i-1,0){
            if(arr[i].ST-arr[i].ND<=arr[j].ST)
                graf[i].PB(j);
            else
                break;
        }
    }

    set<int> zbior; 
    REP(i,1<<n)
        zbior.IN(detonate(i));
    cout<<SIZE(zbior)<<"\n";
}