//by szh
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pii pair<int,int>
#define pll pair<long long,long long>
#define pb push_back
#define debug(x) cerr<<#x<<"="<<x<<endl
#define pq priority_queue
#define inf 0x3f
#define rep(i,a,b) for (int i=a;i<(b);i++)
#define MP make_pair
#define SZ(x) (int(x.size()))
#define ll long long
#define ALL(x) x.begin(),x.end()
const ll big = 1000000000000000000;
ll mod;
int n;
ll a,b;
vector <pll> range;
int main() {
// freopen("input.txt","r",stdin);
std::ios::sync_with_stdio(false);cin.tie();
cin>>n>>a>>b;
ll tmp = __gcd(a,b+1);
tmp = a/tmp;
if (1.0*big/tmp<(double)b) mod = big;
else mod = b*tmp;
debug(mod);
rep(i,0,n) {
ll l,r;cin>>l>>r;
if (l/mod==r/mod) range.pb({l%mod,r%mod});
else range.pb({l%mod,mod-1}),range.pb({0,r%mod});
}
sort(ALL(range));
ll cur = -1,ans=0;
for (auto x:range) {
if (x.fi<=cur) ans+=max(0ll,x.se-cur),cur = max(cur,x.se);
else ans+=x.se-x.fi+1,cur = x.se;
}
cout<<ans;
return 0;
}
