#include <iostream>
#include <algorithm>
using namespace std;
#define int long long
struct wei{
int l;
int r;
};
wei ar[2000005];
int gcd(int x, int y){
if(x*y==0){return x+y;}
if(x<y){swap(x,y);}
return gcd(y, x%y);
}
bool cmp(wei x, wei y){
if(x.r!=y.r){return x.r<y.r;}
return x.l < y.l;
}
signed main()
{
int n,a,b;
int n1,n2;
int pos[2000005];
int con[2000005];
int ll,rr;
cin>>n>>a>>b;
int k = gcd(a, b+1);
int len = a/k;
int ans=0;
int chk=0;
int cur=0;
int don=0;
ar[0].l = -1;
ar[0].r = -1;
pos[0]=0;
if(b > (1e18)/len){len = 1e18 + 5LL;}
else {len *= b;}
for(int i=1; i<=n; i++){
cin>>n1>>n2;
if(n2-n1+1>=len){chk=1;}
n1 %= len;
n2 %= len;
if(n1<=n2){
cur++;
ar[cur].l = n1;
ar[cur].r = n2;
}
else {
cur++;
ar[cur].l = 0;
ar[cur].r = n2;
cur++;
ar[cur].l = n1;
ar[cur].r = len-1;
}
}
sort(ar+1, ar+cur+1, cmp);
ar[0].l = -1;
ar[0].r = -1;
for(int i=1; i<=cur; i++){
while(don>=1){
n1 = pos[don];
if(ar[i].l <= ar[n1].l){
ans -= con[don];
con[don]=0;
don--;
}
else {break;}
}
don++;
pos[don]=i;
con[don] = ar[i].r - max(ar[i].l-1, ar[pos[don-1]].r);
ans += con[don];
}
if(chk==1){cout<<len<<endl;}
else {cout<<ans<<endl;}
}
