#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
// vector<vector<ll>> overlappedInterval(vector<vector<ll>>& intervals) {
// if (intervals.empty()) {
// return vector<vector<ll>>();
// }
// // Sort intervals based on start values
// sort(intervals.begin(), intervals.end(), [](const vector<ll>& a, const vector<ll>& b) {
// return a[0] < b[0];
// });
// stack<vector<ll>> mergedStack;
// mergedStack.push(intervals[0]);
// for (int i = 1; i < intervals.size(); i++) {
// vector<ll> current = intervals[i];
// vector<ll>& top = mergedStack.top();
// if (current[0] <= top[1]) {
// // If current interval overlaps with the top of the stack, merge them
// top[1] = max(top[1], current[1]);
// } else {
// // If no overlap, push the current interval onto the stack
// mergedStack.push(current);
// }
// }
// // Convert the stack to a vector
// vector<vector<ll>> mergedIntervals;
// while (!mergedStack.empty()) {
// mergedIntervals.insert(mergedIntervals.begin(), mergedStack.top());
// mergedStack.pop();
// }
// return mergedIntervals;
// }
struct Interval {
ll s, e;
};
// Function used in sort
bool mycomp(Interval a, Interval b) { return a.s < b.s; }
void mergeIntervals(Interval arr[], ll n)
{
// Sort Intervals in increasing order of
// start time
sort(arr, arr + n, mycomp);
ll index = 0; // Stores index of last element
// in output array (modified arr[])
// Traverse all input Intervals
for (ll i = 1; i < n; i++) {
// If this is not first Interval and overlaps
// with the previous one
if (arr[index].e >= arr[i].s) {
// Merge previous and current Intervals
arr[index].e = max(arr[index].e, arr[i].e);
}
else {
index++;
arr[index] = arr[i];
}
}
// Now arr[0..index-1] stores the merged Intervals
//cout << "\n The Merged Intervals are: ";
ll ans =0;
for (ll i = 0; i <= index; i++) ans+= arr[i].e-arr[i].s+1;
cout<<ans<<"\n";
//cout << "[" << arr[i].s << ", " << arr[i].e << "] ";
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
set<pair<ll, ll>> s;
ll n, A, B; cin>>n>>A>>B;
ll period;
ll X = A/(gcd(B+1, A));
int powX=0, powB=0;
ll xxx = X;
while(xxx>0){
xxx/=2;
powX+=1;
}
xxx=B;
while(xxx>0){
xxx/=2;
powB+=1;
}
if(powB+powX>61) period=4e18;
else period = B*X;
//cout<<period<<"\n";
vector<pair<ll, ll>> v;
for(int i=0; i<n; i++){
ll x, y; cin>>x>>y;
if(y-x<period){
ll XX = x%period;
ll YY = y%period;
if(XX<=YY) v.push_back({XX,YY});
else{
v.push_back({XX, period-1});
v.push_back({0, YY});
}
}
else{
v.push_back({0, period-1});
}
}
Interval arr[int(v.size())];
for(int i=0; i<int(v.size()); i++){
arr[i].s = v[i].first;
arr[i].e = v[i].second;
}
//for(auto p: v) cout<<p.first<<" "<<p.second<<"\n";
// vector<vector<ll>> merged = overlappedInterval(v);
// ll ans =0;
// for(auto vv: merged){
// ans += vv[1]-vv[0]+1;
// }
// cout<<ans<<"\n";
mergeIntervals(arr, int(v.size()));
return 0;
}
