/**
* In the name of Allah
* We are nothing and you're everything
* author: najmuddin
**/
#include <bits/stdc++.h>
using namespace std;
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
#define int ll
//const char nl = '\n';
const int N = 1e7;
int32_t main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, a, b;
cin >> n >> a >> b;
if (b == 1) {
set<pair<int, int>> st, st2;
for (int i = 0; i < n; ++i) {
int l, r; cin >> l >> r;
if (sz(st) == 0)st.insert({l, r}), st2.insert({r, l});
else {
auto it = st.lower_bound({l, 0});
int nl = l, nr = r;
while (it != st.end() && it->first <= r) {
nl = min(nl, it->first);
nr = max(nr, it->second);
st2.erase({it->second, it->first});
st.erase(it);
it = st.lower_bound({l, 0});
}
st.insert({nl, nr});
st2.insert({nr, nl});
nl = l, nr = r;
it = st2.lower_bound({l, 0});
while (it != st2.end() && it->first >= l && it->first <= r) {
nl = min(nl, it->second);
nr = max(nr, it->first);
st.erase({nl, nr});
st2.erase(it);
it = st2.lower_bound({l, 0});
}
st2.insert({nr, nl});
st.insert({nl, nr});
}
}
int ans = 0;
for (auto i: st) {
//cout << i.first << " " << i.second << endl;
ans += i.second-i.first+1;
}
cout << ans;
return 0;
}
set<pair<int, int>> st;
for (int i = 0; i < n; ++i) {
int l, r; cin >> l >> r;
for (int j = l; j <= r; ++j)st.insert({(j+j/b)%a, j%b});
}
cout << sz(st);
return 0;
}
