#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1000005;
const int MAXT = 4200000;
using lint = long long;
using pi = pair<lint, lint>;
lint gcd(lint x, lint y){
return y ? gcd(y, x%y) : x;
}
struct event{
lint pos, st, ed;
int dx;
bool operator<(const event &e)const{
return pos != e.pos ? pos < e.pos : dx > e.dx;
}
};
struct strip{
lint fuck, pos, dx;
bool operator<(const strip &s)const{
return pi(fuck, pos) < pi(s.fuck, s.pos);
}
};
int n;
lint a, b, l[MAXN], r[MAXN];
map<lint, int> mp;
vector<strip> strips;
int main(){
scanf("%d",&n);
scanf("%lld %lld",&a,&b);
for(int i=0; i<n; i++){
scanf("%lld %lld",&l[i],&r[i]);
}
lint period = a / gcd(a, b + 1);
for(int i=0; i<n; i++){
vector<lint> v = {l[i] % b, 0, (r[i] + 1) % b};
sort(v.begin(), v.end());
v.resize(unique(v.begin(), v.end()) - v.begin());
int ptr = 0;
vector<event> tev;
map<lint, int> dx;
int cnt = 0;
for(auto &j : v){
ptr++;
lint s = l[i] + b - j;
lint e = r[i] + b - j;
s = (s + b - 1) / b;
e /= b;
lint is = j;
lint ie = (ptr < v.size() ? v[ptr] : b);
if(e - s + 1 >= period){
tev.push_back({is, 0, period, +1});
tev.push_back({ie, 0, period, -1});
dx[0]++;
dx[period]--;
}
else if(s <= e){
if(s % period > e % period){
tev.push_back({is, s % period, period, +1});
tev.push_back({ie, s % period, period, -1});
tev.push_back({is, 0, e % period + 1, +1});
tev.push_back({ie, 0, e % period + 1, -1});
dx[s % period]++;
dx[period]--;
dx[0]++;
dx[e % period + 1]--;
}
else{
tev.push_back({is, s % period, e % period + 1, +1});
tev.push_back({ie, s % period, e % period + 1, -1});
dx[s % period]++;
dx[e % period + 1]--;
}
}
cnt++;
}
auto nitr = dx.begin();
int tcnt = 0;
for(auto &i : dx){
nitr++;
tcnt += i.second;
if(nitr == dx.end()) break;
if(tcnt == cnt){
mp[i.first]++;
mp[nitr->first]--;
}
else{
for(auto &j : tev){
lint st = max(i.first, j.st);
lint ed = min(nitr->first, j.ed);
for(lint jj = st; jj < ed; jj++){
strips.push_back({jj, j.pos, j.dx});
}
}
}
}
}
auto nitr = mp.begin();
int tcnt = 0;
vector<lint> v;
lint ret = 0;
for(auto &i : mp){
nitr++;
tcnt += i.second;
if(tcnt > 0 && nitr != mp.end()){
ret += b * (nitr->first - i.first);
}
if(tcnt > 0){
v.push_back(i.first);
v.push_back(nitr->first);
}
}
sort(strips.begin(), strips.end());
for(int i=0; i<strips.size(); ){
int e = i;
while(e < strips.size() && strips[e].fuck == strips[i].fuck) e++;
auto l = lower_bound(v.begin(), v.end(), strips[i].fuck + 1) - v.begin();
if(l % 2 == 1){
i = e;
continue;
}
int cnt = 0;
for(int j = i; j + 1 < e; j++){
cnt += strips[j].dx;
if(cnt > 0) ret += strips[j + 1].pos - strips[j].pos;
}
i = e;
}
cout << ret << endl;
}
