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///MEMENTO MEMO, MEMENTO LONG LONG
#include <bits/stdc++.h>

#define DEBUG if(0)
#define COUT cout << "\e[36m"
#define ENDL "\e[39m" << endl
#define VAR(v) " [\e[32m" << #v << "\e[36m=\e[91m" << v << "\e[36m] "

using namespace std;

typedef long long LL;
unsigned int n;

struct Mine
{
    LL pos, r;
};
vector<Mine> field;

string demask(unsigned int mask)
{
    string out;
    for (int i = 0; i < n; ++i) {
        out += (char)((int)(bool)(mask&(1u<<i))+(int)'0');
    }
    return out;
}

unsigned int explode(unsigned int mask)
{
    unsigned int fired = 0;
    for (unsigned int i = 0; i < n; ++i) {
        if(mask&(1u<<i) && !(fired&(1u<<i)))
        {
            fired = fired|(1u<<i);
            LL b= field[i].pos-field[i].r;
            LL e= field[i].pos+field[i].r;
            int lix= i, rix = i;
            while((lix >= 0 && b <= field[lix].pos) || ((rix < n) && field[rix].pos <= e))
            {
                if(lix >= 0 && b <= field[lix].pos)
                {
                    fired = fired|(1u<<lix);
                    b = min(b, field[lix].pos-field[lix].r);
                    e = max(e, field[lix].pos+field[lix].r);
                    lix--;
                }
                if(rix < n && field[rix].pos <= e)
                {
                    fired = fired|(1u<<rix);
                    b = min(b, field[rix].pos-field[rix].r);
                    e = max(e, field[rix].pos+field[rix].r);
                    rix++;
                }

            }


        }
    }
    return fired;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n;
    field.resize(n);
    set<int> results;

    for (unsigned int i = 0; i < n; ++i) {
        cin >> field[i].pos >> field[i].r;
    }

    for (unsigned int mask = 0; mask < 1u<<n; ++mask) {
        results.insert(explode(mask));
    }
    cout << results.size() << "\n";


    return 0;
}