#include <bits/stdc++.h>
using namespace std;
#ifdef ngu
#include "debug.h"
#else
#define debug(...) 42
#endif
const int N = (int) 1e6 + 5;
const long long LIM = (long long) 1e18;
int n, m;
long long a, b, c, res;
long long l[N], r[N];
long long tree[16 * N], lz[16 * N];
vector<long long> rem;
void apply(int id, int l, int r, long long x) {
lz[id] += x;
tree[id] += x * (rem[r + 1] - rem[l]);
}
void upd(int u, int v, long long x, int id = 1, int l = 0, int r = m) {
if (u <= l && r <= v) {
res -= x * tree[id];
apply(id, l, r, x);
return;
}
int mid = l + r >> 1;
if (lz[id]) {
apply(id << 1, l, mid, lz[id]);
apply(id << 1 | 1, mid + 1, r, lz[id]);
lz[id] = 0;
}
if (u <= mid) {
upd(u, v, x, id << 1, l, mid);
}
if (mid < v) {
upd(u, v, x, id << 1 | 1, mid + 1, r);
}
tree[id] = tree[id << 1] + tree[id << 1 | 1];
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
#ifdef ngu
freopen("test.inp", "r", stdin);
freopen("test.out", "w", stdout);
#endif
cin >> n >> a >> b;
if (a <= LIM / b) {
c = a * b;
} else {
c = LIM + 1;
}
rem.emplace_back(0);
rem.emplace_back(c);
for (int i = 1; i <= n; ++i) {
cin >> l[i] >> r[i];
res += r[i] - l[i] + 1;
rem.emplace_back(l[i] % c);
if (l[i] % c - 1 >= 0) {
rem.emplace_back(l[i] % c - 1);
}
rem.emplace_back(r[i] % c);
if (r[i] % c + 1 < c) {
rem.emplace_back(r[i] % c + 1);
}
}
sort(rem.begin(), rem.end());
rem.erase(unique(rem.begin(), rem.end()), rem.end());
m = (int) rem.size() - 2;
auto get_pos = [&](long long i) {
return lower_bound(rem.begin(), rem.end(), i) - rem.begin();
};
for (int i = 1; i <= n; ++i) {
long long cnt = r[i] / c - l[i] / c;
int L = get_pos(l[i] % c);
int R = get_pos(r[i] % c);
if (cnt) {
if (R < L) {
if (R + 1 <= L - 1) {
upd(R + 1, L - 1, cnt - 1);
}
upd(0, R, cnt);
upd(L, m, cnt);
} else {
upd(L, R, cnt + 1);
if (0 <= L - 1) {
upd(0, L - 1, cnt);
}
if (R + 1 <= m) {
upd(R + 1, m, cnt);
}
}
} else {
upd(L, R, 1);
}
}
cout << res;
}
