#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {
cerr<<vars<<" = ";
string delim="";
(...,(cerr<<delim<<values,delim=", "));
cerr<<"\n";
}
#else
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {}
#endif
#define pb push_back
#define sz(x) (int)(x.size())
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<typename T> inline void maxa(T& a,T b){a=max(a,b);}
template<typename T> inline void mina(T& a,T b){a=min(a,b);}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int mxN=2e5+5; //make sure this is right
const int mod=1e9+7;
int main(){
cin.sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#ifdef LOCAL
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif
int n; cin>>n;
ll a,b; cin>>a>>b;
set<pll> seen;
// if(n==1){
// ll l,r; cin>>l>>r;
// cout<<min(r-l+1,a*b)<<"\n";
// } else{
for(int i=0;i<n;i++){
ll l,r; cin>>l>>r;
for(ll j=l;j<=r;j++){
seen.insert({(j+j/b)%a,j%b});
}
}
cout<<sz(seen)<<"\n";
// }
}
