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#include<bits/stdc++.h> 
using namespace std;

//g++ -O3 -static 3B/3B.cpp -std=c++11 -o 3B/3b
/*
4
1 5 2
2 3 0
2 3 6
1 7 4
*/

long long a[300005], r[300005];
bool on[300005];

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin >> n;
    for(int i = 0; i < n; i++){
        cin >> a[i] >> r[i];
    }

    int res = 0;
    for(int i = 0; i < (1 << n); i++){
        for(int j = 0; j < n; j++){
            if((1 << j) & i){
                on[j] = true;
            }else{
                on[j] = false;
            }
        }
        bool incorrect = false;
        for(int x = 0; x < n; x++){
            for(int y = 0; y < n; y++){
                if (x == y){
                    continue;
                }else{
                    if(a[x] - r[x] <= a[y] && a[x] + r[x] >= a[y] && on[x] && !on[y]){
                        incorrect = true;
                        break;
                    }
                }
            }
            if(incorrect){
                break;
            }
        }
        if(!incorrect){
            res++;
        }
    }
    //cout << "finishing program"<<endl;
    cout<<res;
    return 0;
}