#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
#define rep(i, n) for(int i = 1; i <= n; ++i)
#define forn(i, l, r) for(int i = l; i <= r; ++i)
#define ford(i, r, l) for(int i = r; i >= l; --i)
#define FOR(i, n) for(int i = 0; i < n; ++i)
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define endl "\n"
#define task ""
#define sz(a) int(a.size())
#define C(x, y) make_pair(x, y)
#define all(a) (a).begin(), (a).end()
#define bit(i, mask) (mask >> i & 1)
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
inline int readInt() {char c;while(c=getchar(),c!='-'&&(c<'0'||c>'9'));bool sign=(c=='-');if(sign)c=getchar();int n=c-'0';while(c=getchar(),c>='0'&&c<='9')n=10*n+c-'0';return(!sign)?n:-n;}
inline ll readLong() {char c;while(c=getchar(),c!='-'&&(c<'0'||c>'9'));bool sign=(c=='-');if(sign)c=getchar();ll n=c-'0';while(c=getchar(),c>='0'&&c<='9')n=10*n+c-'0';return(!sign)?n:-n;}
inline string readString() {char c;while(c=getchar(),c==' '||c=='\n'||c=='\t');string s({c});while(c=getchar(),c!=EOF&&c!=' '&&c!='\n'&&c!='\t')s+=c;return s;}
const int N = 2e5 + 10;
const int M = 1e3 + 3;
const int N1 = 2e3 + 10;
const int K = 1e2 + 1;
const int MOD = 1e9 + 7;
const ll INF = 1e18;
const ll LINF = 1e17 + 2;
const int block_size = 500;
const int LOG = 29;
const int offset = N;
const int LIM = 1e4 ;
const int AL = 26;
int n;
ll a, b;
vector<pii> p;
void add(int l, int r)
{
p.pb({l, 1});
p.pb({r + 1, -1});
}
void solve()
{
cin >> n >> a >> b;
ll period = a / __gcd(a, b + 1) / INF > b ? INF : a / __gcd(a, b + 1) * b;
rep(i, n)
{
ll l, r;
cin >> l >> r;
--l;
--r;
if(r - l + 1 >= period) return cout << period, void();
l %= period;
r %= period;
if(l > r)
add(0, r), add(l, period - 1);
else
add(l, r);
}
sort(all(p));
int cnt = 0;
ll last = 0;
ll res = 0;
for(int i = 0; i < sz(p); ++i)
{
int j = i;
if(i > 0 && cnt)
res += (p[i].fi - p[i - 1].fi);
while(j < sz(p) && p[i].fi == p[j].fi)
{
cnt += p[j].se;
++j;
}
i = j - 1;
}
cout << res;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int TC = 1;
while(TC--)
{
solve();
cout << endl;
}
return 0;
}
//ha
