// Cao Quang Hung
#include <cassert>
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
using namespace std;
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define pii pair<int,int>
#define pll pair<long long , long long>
#define vi vector<int>
#define vpii vector<pii>
#define SZ(x) ((int)(x.size()))
#define fi first
#define se second
#define IN(x,y) ((y).find((x))!=(y).end())
#define ALL(t) t.begin(),t.end()
#define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define REP(i,a,b) for(int (i)=(a);(i)<=(b);++i)
#define REPD(i,a,b) for(int (i)=(a); (i)>=(b);--i)
#define FOR(i, n) for (int (i) = 0; (i) < (n); ++(i))
#define dem(x) __builtin_popcount(x)
#define Mask(x) (1LL << (x))
#define BIT(x, i) ((x) >> (i) & 1)
#define ln '\n'
#define io_faster ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
///mt19937 rnd(time(0));
const int INF = 1e9 , mod = 1e9 + 7;
template <class T1, class T2>
inline T1 mul(T1& x, const T2 &k){ return x = (1LL * x * k) % mod; }
template <class T1 , class T2>
inline T1 pw(T1 x, T2 k){T1 res = 1; for (; k ; k >>= 1){ if (k & 1) mul(res, x); mul(x, x); } return res;}
template <class T>
inline bool minimize(T &x, const T &y){ if (x > y){x = y; return 1;} return 0; }
template <class T>
inline bool maximize(T &x, const T &y){ if (x < y){x = y; return 1;} return 0; }
template <class T>
inline void add(T &x , const T &y){ if ((x += y) >= mod) x -= mod; }
template <class T>
inline T product (const T &x , const T &y) { return 1LL * x * y % mod; }
#define PROB "a"
void file(){
if(fopen(PROB".inp", "r")){
freopen(PROB".inp","r",stdin);
freopen(PROB".out","w",stdout);
}
}
void sinh_(){
// srand(time(0));
// freopen(PROB".inp" , "w" , stdout);
// int n;
}
typedef long long ll;
typedef double db;
const int N = 1e6 + 5;
int n;
ll A, B, l[N], r[N];
void readip(){
cin >> n >> A >> B;
REP(i, 1, n) cin >> l[i] >> r[i];
}
namespace sub1{
bool check() {
ll s = 0;
REP(i, 1, n) s += r[i] - l[i] + 1;
return s <= 1e6;
}
void solve() {
vector<pair<ll, ll>> distinct;
REP(i, 1, n) {
for (ll x = l[i]; x <= r[i]; ++x)
distinct.eb((x + x / B) % A , x % B);
}
sort(ALL(distinct));
distinct.erase(unique(ALL(distinct)), distinct.end());
cout << distinct.size() << ln;
}
};
namespace sub2{
void solve() {
if (A & 1) {
// cycle size A
vector<pair<ll, ll>> segments[2];
REP(i, 1, n) {
ll lef = (2LL * l[i]) % A, rig = (2LL * r[i]) % A;
if (lef % 2 != rig % 2) {
if (lef % 2 == 0) {
segments[0].eb(lef, A - 1);
segments[1].eb(1, rig);
}
else {
segments[1].eb(lef, A - 2);
segments[0].eb(0, rig);
}
}
else segments[lef % 2].eb(lef, rig);
}
ll res = 0;
FOR(i, 2) {
if (segments[i].empty()) continue;
sort(ALL(segments[i]));
vector<pair<ll, ll>> hihi;
hihi.eb(segments[i][0]);
for (int j = 1; j < segments[i].size(); ++j) {
ll r = segments[i][j].second;
ll l = segments[i][j].first;
if (r <= hihi.back().se) continue;
if (l <= hihi.back().se) hihi.back().se = r;
else hihi.eb(l, r);
}
for (auto it : hihi)
res += (it.se - it.fi) / 2 + 1;
}
cout << res << ln;
}
else {
// cycle size A / 2
vector<pair<ll, ll>> segments;
REP(i, 1, n) {
ll lef = (2LL * l[i]) % A;
ll rig = (2LL * r[i]) % A;
ll tmp = (A - lef) / 2;
if (r[i] - l[i] + 1 <= tmp) {
segments.eb(lef, rig);
}
else {
segments.eb(lef, A - 2);
segments.eb(0, rig);
}
}
ll res = 0;
if (segments.empty()) {
cout << 0 << ln;
return;
}
vector<pair<ll, ll>> hihi;
hihi.eb(segments[0]);
REP(i, 1, segments.size() - 1) {
ll r = segments[i].second;
ll l = segments[i].first;
if (r <= hihi.back().se) continue;
if (l <= hihi.back().se) hihi.back().se = r;
else hihi.eb(l, r);
}
for (auto it : hihi)
res += (it.se - it.fi) / 2 + 1;
cout << res << ln;
}
}
};
void solve(){
if (sub1::check()) {
sub1::solve();
return;
}
if (B == 1) {
sub2::solve();
return;
}
// int m = 50;
// for (int i = 35; i <= 10000; i += m) {
// REP(j, 0, m - 1) cout << ((i + j) * 2) % m << ' ';
// cout << ln;
// }
}
int main(){
sinh_();
io_faster
file();
int t = 1;
// cin >> t;
while (t--){
readip();
solve();
}
}
