#include <time.h>
#include <cstdlib>
#include <stack>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
#include <map>
#include <set>
#include <iterator>
#include <deque>
#include <queue>
#include <sstream>
#include <array>
#include <string>
#include <tuple>
#include <chrono>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <list>
#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <bitset>
#define ll long long
using namespace std;
ll n, A, B;
ll l[1000005], r[1000005], sum = 0;
set<pair<ll, ll>> st1, st2, st;
int main(){
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
cin >> n >> A >> B;
for(int i = 1; i <= n; i++){
cin >> l[i] >> r[i];
sum += (r[i] - l[i] + 1);
}
if(sum <= 1e6){
for(int i = 1; i <= n; i++){
for(ll j = l[i]; j <= r[i]; j++){
ll x = (j + j / B) % A, y = (j % B);
st.insert({x, y});
}
}
cout << int(st.size()) << "\n";
return 0;
}
if(n == 1){
ll x = (l[1] + l[1] / B) % A;
if(l[1] + B <= r[1]){
ll num = l[1] + B;
ll y = (num + num / B) % A;
if(x == y){
cout << B << "\n";
return 0;
}
ll d = abs(x - y);
ll ans = gcd(d, A);
ll rg = l[1] + ans * B - 1;
cout << min(r[1], rg) - l[1] + 1 << "\n";
}
else{
cout << r[1] - l[1] + 1 << "\n";
return 0;
}
}
ll lf[n + 2], rg[n + 2];
for(int i = 1; i <= n; i++){
lf[i] = l[i];
rg[i] = min(r[i], l[i] + A - 1);
st1.insert({lf[i], i});
st2.insert({rg[i], i});
}
ll ans = 0, mx = 0, mn = 0;
bool f = 0;
while(!st1.empty()){
if(!f){
auto it = st1.begin();
mn = it->first;
mx = rg[it->second];
f = 1;
st1.erase(st1.begin());
continue;
}
else{
if(st1.begin()->first <= mx){
auto it = st1.begin();
mx = max(rg[it->second], mx);
st1.erase(st1.begin());
continue;
}
else{
ans += (mx - mn + 1);
auto it = st1.begin();
mn = it->first;
mx = rg[it->second];
f = 1;
st1.erase(st1.begin());
}
}
}
ans += (mx - mn + 1);
cout << ans;
}
