// author : sentheta aka vanwij
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<cassert>
#include<random>
#include<chrono>
#include<cmath>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<stack>
#include<map>
#include<set>
using namespace std;
#define Int long long
#define V vector
#define pii pair<int,int>
#define ff first
#define ss second
#define rand() (uniform_int_distribution<int>(0,1<<30)(rng))
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pow2(x) (1LL<<(x))
#define msb(x) (63-__builtin_clzll(x))
#define bitcnt(x) (__builtin_popcountll(x))
#define nl '\n'
#define _ << ' ' <<
#define all(x) (x).begin(), (x).end()
#define rep(i,a,b) for(int i = (int)(a); i < (int)(b); i++)
#define dbg(x) if(1) cout << "?" << #x << " : " << (x) << endl << flush;
#define int long long
const Int MOD = 1e9+7;
//const Int MOD = 998244353;
Int bpow(Int a,Int b){
Int ret = 1;
for(;b; a=a*a%MOD,b/=2) if(b&1) ret = ret*a%MOD;
return ret;
}
Int inv(Int a){return bpow(a,MOD-2);}
void solve(); int TC;
signed main(){ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
srand(chrono::steady_clock::now().time_since_epoch().count());
cout << fixed << setprecision(7);
///cin >> TC; while(TC--) solve(); return 0;
solve();
}
int n;
int A, B;
int len;
pii f(int x){
return {(x+x/B)%A, x%B};
}
void solve(){
cin >> n >> A >> B;
if(A/gcd(A,B+1)*((double)(B)) > 1e18+5){
len = 1e18+5;
}
else len = A/gcd(A,B+1)*B;
//dbg(len);
//set<pii> s;
//rep(i,0,len) s.insert(f(i));
//assert((int)s.size()==len);
//rep(i,len,1e7) assert(f(i)==f(i-len));
//return;
priority_queue<pii> pq;
rep(i,0,n){
int l, r;
cin >> l >> r;
if(r-l+1 >= len){
cout << len << nl; return;
}
l %= len; r %= len;
if(l <= r){
pq.push({-l, r});
}
else{
pq.push({-l, len-1});
pq.push({0, r});
}
}
int ans = 0;
int l = -1, r = -2;
while(!pq.empty()){
auto[tl,tr] = pq.top(); pq.pop();
tl *= -1;
//cout << tl _ tr << nl;
if(r < tl){
ans += r-l+1;
l = tl; r = tr;
}
else{
r = max(r, tr);
}
}
ans += r-l+1;
cout << ans << nl;
}
