#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pb push_back
//#define mp make_pair
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;
const int N = 3e6 + 5;
const int oo = 1e18 + 7, mod = 1e9 + 7;
/*
What I'm trying to do:
Just imagine that we want all intervals that begins with (sth, 0) to ((sth + B - 1) % A, B - 1), the rest
has like O(n) segments. Inside this interval, there will be no changes made to t/B
Ez as hell
*/
int n, a, b;
//vector<int> inters[N];
vector<ii> full;
unordered_map<int, int> mp;
bool ok[N];
vector<ii> part[N];
int cnt;
void process(){
cin >> n >> a >> b;
int temp = __gcd(a, b + 1);
for(int i = 1; i <= n; i++){
int x, y;
cin >> x >> y;
int temp1 = x / b + 1, temp2 = y / b - 1;
if(temp1 <= temp2){
if((temp2 - temp1 + 1) >= a/temp){
cout << a * b / temp;
exit(0);
}
temp1 %= a/temp, temp2 %= a/temp;
if(temp1 <= temp2) full.pb({temp1, temp2});
else{
full.pb({temp1, a/temp - 1});
full.pb({0, temp2});
}
}
if((x/b) == (y/b)){
if(mp.find((x/b) % (a/temp)) == mp.end()){
cnt++;
mp[(x/b) % (a/temp)] = cnt;
}
// cout << x << " " << y << " " << cnt << " " << x%b << " " << y%b << "\n";
part[mp[(x/b) % (a/temp)]].pb({x % b, y % b});
}
else{
//temp1 = , temp2 = (y / b) * b;
if(mp.find((x/b) % (a/temp)) == mp.end()){
cnt++;
mp[(x/b) % (a/temp)] = cnt;
}
part[mp[(x/b) % (a/temp)]].pb({x % b, b - 1});
//cout << x << " " << y << " " << cnt << " " << x%b << " " << b-1 << "\n";
if(mp.find((y/b) % (a/temp)) == mp.end()){
cnt++;
mp[(y/b) % (a/temp)] = cnt;
}
part[mp[(y/b) % (a/temp)]].pb({0, y % b});
// cout << x << " " << y << " " << cnt << " " << 0 << " " << y%b << "\n";
}
}
//sort(full.begin(), full.end());
vector<ii> updates;
for(auto it : full){
updates.pb({it.fi, 1});
updates.pb({it.se + 1, -1});
}
for(auto it : mp) updates.pb({it.fi, oo});
sort(updates.begin(), updates.end());
int lst = -oo, sum = 0, ans = 0;
for(auto it : updates){
if(lst != -oo) ans += b * (it.fi - lst) * (sum != 0);
lst = it.fi;
if(abs(it.se) == 1) sum += it.se;
if(it.se == oo) ok[mp[it.fi]] = (sum == 0);
}
// cout << ans << "\n";
// for(auto it : mp) cout << it.fi << " " << it.se << "\n";
for(int i = 1; i <= cnt; i++){
if(!ok[i]) continue;
//sort(part[i].begin(), part[i].end());
vector<ii> upds;
for(auto it : part[i]){
// cout << i << " " << it.fi << " " << it.se << "\n";
upds.pb({it.fi, 1});
upds.pb({it.se + 1, -1});
}
sort(upds.begin(), upds.end());
int lst = -oo, sum = 0;
for(auto it : upds){
// cout << "OK " << sum << " " << lst << " " << it.fi << "\n";
if(lst != -oo) ans += (it.fi - lst) * (sum != 0);
sum += it.se;
lst = it.fi;
}
// cout << ans << "\n";
}
cout << ans << "\n";
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("device.inp", "r", stdin);
//freopen("device.out", "w", stdout);
process();
}
