#include <stdio.h>
#include <stdlib.h>

// minimum a maximum
#define MIN(X,Y) ((X) < (Y) ? (X) : (Y))
#define MAX(X,Y) ((X) > (Y) ? (X) : (Y))

struct MF {
    int start;
    int cil;
} mff[1000001];


// porovnávací funkce pro Quicksort
// makro poslouží pro zjednodušení zápisu
#define R(x) ((struct MF*) x)->cil

int cmp(const void *a, const void *b)
{
    return (R(a) - R(b));
}

int main(void)
{
    int a, b, k, n, o, p, i;
    FILE *fin, *fout;
    fin=fopen("kolej.in", "r");
    fscanf(fin, "%d %d\n", &n, &k);
    for (i = 0; i < n; i++)
    {
        fscanf(fin, "%d %d\n", &p, &o);
        mff[i].start = MAX(1, p-o);
        mff[i].cil=MIN(k, p+o);
    }
    fclose(fin);
    qsort(mff, n, sizeof(struct MF), cmp);

    b = 0;
    a = 0;
    for (i = 0; i < n; i++)
    {
        if (mff[i].start > b)
        {
            b = mff[i].cil;
            a++;
        }
    }

    fout = fopen("zastavky.out", "w");
    fprintf(fout, "%d\n", a);
    fclose(fout);
    return 0;

}