#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 1e6 + 6;
const long long inf = 1e18;
int n;
long long a, b;
void solve() {
cin >> n >> a >> b;
long long d = __gcd(b + 1, a);
if (inf / b < a / d) {
long long res = 0;
for (int i = 1; i <= n; ++i) {
long long l, r; cin >> l >> r;
res += (r - l + 1);
}
cout << res;
return;
}
long long g = (a / d) * b;
// debug(g);
map<long long, int> mp;
for (int i = 1; i <= n; ++i) {
long long l, r; cin >> l >> r;
if (r - l >= g) {
cout << g << '\n';
return;
}
l %= g, r %= g;
++mp[l], --mp[r + 1];
if (l > r) {
++mp[0];
--mp[g];
}
}
long long res = 0;
long long prv = 0;
long long cur = 0;
for (auto [x, y] : mp) {
if (cur == 0) {
res += x - prv;
}
cur += y;
if (cur == 0) {
prv = x;
}
}
res += (g - prv);
cout << g - res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
