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/// Radoslaw Mysliwiec 2020
#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace __gnu_pbds;
using namespace std;
 
#define F first
#define S second
#define PB push_back
#define ALL(x) (x).begin(),(x).end()
#define endl '\n'
#define dd cout << " debug";
 
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vll = vector<ll>;
using pi = pair<int,int>;
using pll = pair<ll,ll>;
using matrix = vector<vll>;
using ordered_set = tree<pi, null_type, less<pi>, rb_tree_tag, tree_order_statistics_node_update>;
 
ll pos[300300], radius[300300], r[300300], l[300300], n;
vector<bool> done(100000000, 0);
 
int main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> n;
    for (int i=0; i<n; ++i){
        cin >> pos[i] >> radius[i];
    }
    int x, res = 0;
    for (int i=0; i<(1<<n); ++i) {
        x = 0;
        for (int j=0; j<n; ++j) {
            if ((i>>j) & 1) {
                l[j] = pos[j] - radius[j];
                r[j] = pos[j] + radius[j];
                int L = j, R = j;
                while (L >= 0 || R < n) {
                    bool change = 0;
                    if (L >= 0 && l[j] <= pos[L]) {
                        x |= (1<<L);
                        l[j] = min(l[j], pos[L] - radius[L]);
                        r[j] = max(r[j], pos[L] + radius[L]);
                        --L;
                        change = 1;
                    }
                    if (R < n && r[j] >= pos[R]) {
                        x |= (1<<R);
                        l[j] = min(l[j], pos[R] - radius[R]);
                        r[j] = max(r[j], pos[R] + radius[R]);
                        ++R;
                        change = 1;
                    }
                    if (change == 0)
                        break;
                }
            }
        }
        if (!done[x]) {
            ++res;
            done[x] = true;
            /*
            cout << "{";
            vi result;
            for (int i=1; i<=n; ++i){
                if ((x>>(i-1))&1)
                    result.PB(i);
            }
            for (int i=0; i<result.size(); ++i) {
                if (i == 0) cout << result[i];
                else cout << ", " << result[i]; 
            }
            cout << "}\n";*/
        }
    }
    cout << res << endl;
}