#include <stdio.h>
#define N 1000000
long long gcd(long long a, long long b) {
return b == 0 ? a : gcd(b, a % b);
}
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
long long xx[N], yy[N];
void sort(int *ii, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;
while (j < k) {
long long c = xx[ii[j]] != xx[i_] ? xx[ii[j]] - xx[i_] : yy[ii[j]] - yy[i_];
if (c == 0)
j++;
else if (c < 0) {
tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
i++, j++;
} else {
k--;
tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
}
}
sort(ii, l, i);
l = k;
}
}
int main() {
static int ii[N];
int n, n_, i, ans;
long long a, b;
scanf("%d%lld%lld", &n, &a, &b);
if (n == 1) {
long long l, r, k;
scanf("%lld%lld", &l, &r);
k = a / gcd(a, b + 1);
printf("%lld\n", k <= (r - l + 1) / b ? k * b : r - l + 1);
return 0;
}
n_ = 0;
while (n--) {
long long l, r;
scanf("%lld%lld", &l, &r);
while (l <= r) {
xx[n_] = (l + l / b) % a, yy[n_] = l % b, n_++;
l++;
}
}
n = n_;
for (i = 0; i < n; i++)
ii[i] = i;
sort(ii, 0, n);
ans = 1;
for (i = 1; i < n; i++)
if (xx[ii[i]] != xx[ii[i - 1]] || yy[ii[i]] != yy[ii[i - 1]])
ans++;
printf("%d\n", ans);
return 0;
}
