import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv, std.math,
    std.functional, std.numeric, std.range, std.stdio, std.string, std.random,
    std.typecons, std.container, std.format;
static import std.ascii;

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);
// dfmt on

void main()
{
    long N = lread();
    auto X = new long[](N);
    auto L = new long[](N);
    foreach (i; 0 .. N)
        scan(X[i], L[i]);
    zip(X, L).sort();
    auto left = new long[](N);
    foreach (i; 0 .. N)
        left[i] = X[i] - L[i];

    long cnt(long x, long s) // left[s<=i] < x となるiの数
    {
        long ok = s;
        long ng = N;
        while (1 < ng - ok)
        {
            long m = (ok + ng) / 2;
            if (left[m] < x)
            {
                ok = m;
            }
            else
            {
                ng = m;
            }
        }
        return ok - s;
    }

    long ans;
    long cur = long.min;
    foreach (i; 0 .. N)
        if (cur <= X[i] - L[i])
        {
            long c = cnt(X[i] + L[i], i);
            // writeln(i, " ", c);
            if (c < 2) //X[i] + L[i] <= a || X[i] + L[i] <= b)
            {
                // writeln("a");
                cur = X[i] + L[i];
                ans++;
            }
        }
    writeln(ans);
}
