#include <bits/stdc++.h>
using namespace std;
#define int long long
#define sp << ' ' <<
#define nl << '\n'
const int INF = 1e18;
bool comp(array<int, 2> &x, array<int, 2> &y){
return x[1] < y[1];
}
signed main(){
cin.tie(0)->sync_with_stdio(0);
int n, A, B, l, r; cin >> n >> A >> B;
int g = A / __gcd(A, B + 1LL);
if(g > (INF + 5LL) / B) g = INF + 5;
else g *= B;
vector<array<int, 2>> q;
bool all = false;
while(n--){
cin >> l >> r;
int lm = l % g, rm = r % g;
// if(l + (g - lm) <= r) q.push_back({lm, g-1}), q.push_back({0, rm});
// else q.push_back({lm, rm});
all = all or (r - l + 1LL >= g);
if(lm <= rm) q.push_back({lm, rm});
else q.push_back({lm, g-1LL}), q.push_back({0, rm});
}
int res = 0;
l = -1, r = -2;
sort(q.begin(), q.end(), comp);
for(auto &i : q){
if(r < i[0]){
res += r - l + 1LL;
l = i[0], r = i[1];
}else r = i[1], l = min(l, i[0]);
}
res += r - l + 1LL;
if(all) res = g;
cout << res;
}
