#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define endl '\n'
#define fi first
#define se second
#define For(i, l, r) for (auto i = (l); i < (r); i++)
#define ForE(i, l, r) for (auto i = (l); i <= (r); i++)
#define FordE(i, l, r) for (auto i = (l); i >= (r); i--)
#define Fora(v, a) for (auto v: (a))
#define bend(a) (a).begin(), (a).end()
#define isz(a) ((signed)(a).size())
using ll = long long;
using ld = long double;
using pii = pair <int, int>;
using vi = vector <int>;
using vpii = vector <pii>;
using vvi = vector <vi>;
const int N = 1e6 + 5;
int n; ll A, B;
ll ans;
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("KEK.inp", "r", stdin);
// freopen("KEK.out", "w", stdout);
cin >> n >> A >> B;
__int128 G = (__int128)(A / __gcd(A, B + 1)) * B;
if (G > (__int128)1e18){
map <ll, ll> mpp;
while (n--){
ll l, r; cin >> l >> r;
mpp[l]++; mpp[r + 1]--;
}
int cnt = 0; ll l = 0;
Fora(elem, mpp){
ll r = elem.fi;
if (cnt != 0){
ans += r - l;
}
cnt += elem.se;
l = r;
}
cout << ans << endl;
return 0;
}
ll g = G;
map <ll, ll> mpp;
while (n--){
ll l, r; cin >> l >> r;
if (r - l + 1 >= g){
cout << g << endl;
return 0;
}
l %= g; r %= g;
if (l <= r){
mpp[l]++; mpp[r + 1]--;
}
else{
mpp[l]++; mpp[g]--; mpp[0]++; mpp[r + 1]--;
}
}
int cnt = 0; ll l = 0;
Fora(elem, mpp){
ll r = elem.fi;
if (cnt != 0){
ans += r - l;
}
cnt += elem.se;
l = r;
}
cout << ans << endl;
}
/*
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INPUT: |
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OUTPUT: |
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*/
