#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#include<bits/stdc++.h>
using namespace std;
#define mp make_pair
#define INF 10000000
#define MOD 1000000007
#define MID (l+r)/2
#define HASHMOD 2305843009213693951
#define ll long long
#define ull unsigned long long
#define F first
#define S second
typedef pair<ll, ll> ii;
typedef pair<ii, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef map<int, int> mii;
#define EPS 1e-6
#define T double
typedef complex<T> pt;
#define x real()
#define y imag()
T dot(pt v, pt w) {return (conj(v)*w).x;}
T cross(pt v, pt w) {return (conj(v)*w).y;}
T orient(pt a, pt b, pt c) {return cross(b-a,c-a);}
T dist(pt a, pt b) {return abs(a-b);}
int main(){
int n, A, B;
cin>>n>>A>>B;
set<ii> s;
for(int i=0;i<n;i++){
int l, r;
cin>>l>>r;
for(int j=l;j<=r;j++){
s.insert(ii((j+j/B)%A, j%B));
}
}
cout<<s.size()<<endl;
}
