#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 1e6 + 5;
const ll oo = 1e18 + 10;
int n;
ll A, B;
ll l[N], r[N];
ll GCD(ll A, ll B) {
if (A < B) swap(A, B);
while (B) {
A %= B;
swap(A, B);
}
return A;
}
int main() {
cin.tie(0) -> sync_with_stdio(0);
cin >> n >> A >> B;
for (int i = 1; i <= n; i++) cin >> l[i] >> r[i];
ll temp = (B + 1) % A;
ll diff;
if (!temp) diff = B;
else {
ll gcd = GCD(temp, A);
temp = A / gcd;
if (oo / temp < B) diff = oo;
else diff = temp * B;
}
if (diff == oo) {
ll ans = 0;
for (int i = 1; i <= n; i++) ans += r[i] - l[i] + 1;
cout << ans;
}
else {
#define pa pair<ll, ll>
#define fi first
#define se second
vector<pa> v;
for (int i = 1; i <= n; i++) {
ll L = l[i] % diff, R = r[i] % diff;
ll hL = l[i] / diff, hR = r[i] / diff;
if (hR - hL > 2 || (hR - hL == 1 && R >= L - 1))
return cout << diff, 0;
if (hR == hL) v.emplace_back(L, R);
else {
v.emplace_back(L, diff - 1);
v.emplace_back(0, R);
}
}
sort(begin(v), end(v));
ll curL = 0, curR = -1;
ll ans = 0;
for (auto i: v) {
if (i.fi > curR) {
ans += curR - curL + 1;
curR = i.se;
curL = i.fi;
}
else curR = max(curR, i.se);
}
ans += curR - curL + 1;
cout << ans;
}
return 0;
}
