#include <time.h>
#include <cstdlib>
#include <stack>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
#include <map>
#include <set>
#include <iterator>
#include <deque>
#include <queue>
#include <sstream>
#include <array>
#include <string>
#include <tuple>
#include <chrono>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <list>
#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <bitset>
#define ll long long
using namespace std;
ll n, A, B;
ll l[1000005], r[1000005], sum = 0;
set<pair<ll, ll>> st;
int main(){
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
cin >> n >> A >> B;
for(int i = 1; i <= n; i++){
cin >> l[i] >> r[i];
sum += (r[i] - l[i] + 1);
}
if(sum <= 1e6){
for(int i = 1; i <= n; i++){
for(ll j = l[i]; j <= r[i]; j++){
ll x = (j + j / B) % A, y = (j % B);
st.insert({x, y});
}
}
cout << int(st.size()) << "\n";
return 0;
}
}
