//oj.uz/problem/view/APIO19_strange_device
//already.
#ifndef LOCAL
#define NDEBUG 1
#endif
#include<bits/stdc++.h>
int main(){
std::ios::sync_with_stdio(0);std::cin.tie(0);
int number; int64_t a, b;
std::cin>>number>>a>>b;
auto const c=a/std::gcd(a, b+1);
int64_t const period=(double)b*(double)c>2e18 ? INT64_MAX: b*c;
struct Event{
bool open: 1;
uint64_t position: 63;
uint64_t key() const{
uint64_t result=position<<1|open;
assert(result==*(uint64_t*) this);
return result;
//return position;
}
bool operator<(Event it) const{
return key()<it.key();
}
};
std::vector<Event> events; events.reserve(number*4);
auto const addSegment=[&](int64_t first, int64_t sec){
assert(first<sec);
events.push_back({true, (((uint64_t)1<<63)-1)&first});
events.push_back({false, (((uint64_t)1<<63)-1)&sec});
};
for(int _=0; _<number; ++_){
int64_t first, sec; std::cin>>first>>sec;
++sec;
if(sec-first>=period){
std::cout<<period<<'\n';
return 0;
}
first%=period; sec%=period;
if(first<sec){
addSegment(first, sec);
}else{
assert(first!=sec);
addSegment(first, period);
if(sec) addSegment(0, sec);
}
}
std::sort(begin(events), end(events));
int64_t result{};
int degree{};
for(auto [open, position]: events){
if(open){
if(degree==0) result-=position;
++degree;
}else{
--degree;
if(degree==0) result+=position;
//assert(degree>=0);
//actually this is not guaranteed because of how stuff are sorted...
}
}
std::cout<<result<<'\n';
}
