#include <bits/stdc++.h>
using namespace std;
string toString(__int128 x) {
if(x == 0) return "0";
bool neg = false;
if(x < 0) { neg = true; x = -x; }
string s;
while(x > 0) {
int d = (int)(x % 10);
s.push_back('0' + d);
x /= 10;
}
if(neg) s.push_back('-');
reverse(s.begin(), s.end());
return s;
}
ostream& operator<<(ostream &out, const __int128 &x) {
out << toString(x);
return out;
}
struct Interval {
__int128 l, r; // 0 <= l <= r < T
};
long long gcd_ll(long long a, long long b){
while(b){
long long t = a % b;
a = b;
b = t;
}
return a;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
long long A_ll, B_ll;
cin >> n >> A_ll >> B_ll;
__int128 A = A_ll, B = B_ll;
vector<pair<__int128, __int128>> intervals;
intervals.reserve(n);
for (int i = 0; i < n; i++){
long long l_ll, r_ll;
cin >> l_ll >> r_ll;
__int128 l = l_ll, r = r_ll;
intervals.push_back({l, r});
}
long long Bplus1_ll = B_ll + 1;
long long g_ll = gcd_ll(A_ll, Bplus1_ll);
__int128 p = A / g_ll;
__int128 T = p * B;
vector<Interval> modIntervals;
bool coversFull = false;
for(auto &seg : intervals){
__int128 l = seg.first, r = seg.second;
__int128 len = r - l + 1;
if(len >= T) {
coversFull = true;
break;
}
__int128 start = l % T;
__int128 end = (l + len - 1) % T;
if(start <= end) {
modIntervals.push_back({start, end});
} else {
modIntervals.push_back({start, T - 1});
modIntervals.push_back({0, end});
}
}
__int128 result = 0;
if(coversFull){
result = T;
} else {
sort(modIntervals.begin(), modIntervals.end(), [](const Interval &a, const Interval &b){
return a.l < b.l;
});
__int128 curL = modIntervals[0].l, curR = modIntervals[0].r;
for (size_t i = 1; i < modIntervals.size(); i++){
if(modIntervals[i].l <= curR + 1) {
curR = max(curR, modIntervals[i].r);
} else {
result += (curR - curL + 1);
curL = modIntervals[i].l;
curR = modIntervals[i].r;
}
}
result += (curR - curL + 1);
}
cout << result << "\n";
return 0;
}
