#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define jizz ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define pb push_back
#define MP make_pair
#define F first
#define S second
#define ET cout << "\n"
#define MEM(i,j) memset(i,j,sizeof i)
#define ALL(v) v.begin(),v.end()
#define DB(a,s,e) {for(int i=s;i<e;++i) cerr << a[i] << " ";ET;}
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
vector<pll> v;
int main()
{jizz
ll n,a,b,l,r,ans=0,g;
__int128 cycle;
cin >> n >> a >> b,g=a/__gcd(b+1,a),cycle=(__int128)g*b;
for(int i=1;i<=n;++i)
{
cin >> l >> r;
if((__int128)(r-l+1)>=cycle)
return cout << (ll)cycle << "\n",0;
if(l%cycle<=r%cycle)
v.pb(MP((ll)l%cycle,(ll)r%cycle));
else
v.pb(MP((ll)l%cycle,(ll)cycle-1)),v.pb(MP(0LL,(ll)r%cycle));
}
sort(ALL(v)),r=-1;
for(auto i:v)
{
if(i.F<=r) ans+=max(i.S-r,0LL),r=max(i.S,r);
else ans+=i.S-i.F+1,r=i.S;
}
cout << ans << "\n";
}
