#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define FileName "test"
#define ll long long
#define ld long double
#define ull unsigned long long
#define Debug(x) cerr << #x << "is " << x << '\n';
#define pb emplace_back
#define mp make_pair
#define x first
#define y second
//#define LuckyAurora
//#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
//#pragma GCC optimization ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
using namespace std;
template<typename T> inline void Cin(T &x)
{
char c;
T sign = 1;
x = 0;
for (c = getchar(); c < '0' || c > '9'; c = getchar())
if (c == '-') sign = -1;
for (; c >= '0' && c <= '9'; c = getchar())
x = x * 10 + c - '0';
x *= sign;
}
template <typename T> inline void Out(T x) {if(x > 9) Out(x / 10); putchar(x % 10 + '0');}
template <typename T> inline void Cout(T x, char c) {if(x < 0) putchar('-'); x = abs(x); Out(x); putchar(c);}
template <typename T, typename... Args> inline void Cin(T& a, Args&... args) {Cin(a);Cin(args...);}
template <typename T, typename... Args> inline void Cout(T a, char c, Args... args) {Cout(a, c);Cout(args...);}
typedef pair<int, int> pii;
const int N = int(1e6) + 1;
struct TIrene {
ll l, r;
TIrene(ll l = 0, ll r = 0): l(l), r(r) {}
bool operator<(const TIrene& o)const& {
return l < o.l || (l == o.l && r < o.r);
}
};
vector<TIrene> v;
int n;
ll A, B, l, r, irene, Irene, low, high, res;
const ll inf = (ll)1e18;
// A / GCD(A, B + 1) * B
ll GCD(ll a, ll b)
{
ll r;
if(a < b) swap(a, b);
while(b) {
r = a % b;
a = b, b = r;
}
return a;
}
ll Pos(ll x)
{
if(inf >= Irene) return x % Irene;
return x;
}
void Enter()
{
cin >> n >> A >> B;
irene = A / GCD(A, B + 1);
Irene = LLONG_MAX;
if(inf / irene >= B) Irene = B * irene;
for(int i = 0; i < n; ++i) {
cin >> l >> r;
if(r - l + 1 >= Irene) {cout << Irene; exit(0);}
low = Pos(l), high = Pos(r);
//cout << low << ' ' << high << '\n';
if(high >= low) v.pb(low, high);
else v.pb(low, Irene - 1), v.pb(0, high);
}
sort(v.begin(), v.end());
}
void Solve()
{
res = 0, high = -2, low = -1;
for(int i = 0; i < int(v.size()); ++i) {
if(v[i].l > high) {
res += high - low + 1;
low = v[i].l, high = v[i].r;
} else high = max(high, v[i].r);
}
res += high - low + 1;
cout << res;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if(fopen(FileName".inp", "r")) {
freopen(FileName".inp", "r", stdin);
freopen(FileName".out", "w", stdout);
}
/*int nTest; cin >> nTest;
while(nTest --)*/ Enter(), Solve();
return 0;
}
