#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>
using namespace std;
#define ll long long
#define ff first
#define ss second
#define mk make_pair
#define pb push_back
#define __fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define MOD 1000000007
map<pair<ll,ll>,ll> mp;
int main(){
__fast
ll n,a,b;
cin>>n>>a>>b;
for(int i=1; i<=n; i++){
ll l,r;
cin>>l>>r;
for(ll j=l; j<=r; j++){
ll x=(j+j/b)%a;
ll y=j%b;
mp[mk(x,y)]++;
}
}
cout<<mp.size();
}
