#include<bits/stdc++.h>
template<class T> inline void read(T &x){
x=0; register char c=getchar(); register bool f=0;
while(!isdigit(c))f^=c=='-',c=getchar();
while(isdigit(c))x=x*10+c-'0',c=getchar(); if(f)x=-x;
}
template<class T> inline T gcd(T n,T m){return m?gcd(m,n%m):n;}
const int N=1e6+10;
int n;
long long A,B,l,r,ans;
std::map<long long,int> sum;
int main(){
#ifdef memset0
freopen("1.in","r",stdin);
#endif
read(n),read(A),read(B);
A/=gcd(A,B+1);
if(A>(long long)(2e18)/B){
for(int i=1;i<=n;i++){
read(l),read(r);
ans+=r-l+1;
}
printf("%lld\n",ans);
return 0;
}
// printf("%lld %lld\n",A,B);
for(int i=1;i<=n;i++){
read(l),read(r);
if(r-l+1>=A*B){
printf("%lld\n",A*B);
return 0;
}
l%=A*B,r%=A*B;
// printf("> %lld %lld\n",l,r);
if(l<=r){
sum[l]++,sum[r+1]--;
}else{
sum[0]++,sum[r+1]--;
sum[l]++,sum[A*B]--;
}
}
sum[A*B]+=0;
long long cnt=0,lst=0;
for(const auto &it:sum){
if(cnt)ans+=it.first-lst;
cnt+=it.second;
lst=it.first;
}
printf("%lld\n",ans);
}
