CF1029C Maximal Intersection

https://www.luogu.org/problem/show?pid=CF1029C

 #include<bits/stdc++.h>
 using namespace std ;
 #define LL long long 

 LL read(){
     char c ;
     int sign =  ;
     while((c = getchar()) > '' || c < '')
         if(c == '-') sign = - ;
     LL ans = c - '' ;
     while((c = getchar()) <='' && c >= '')
         ans = ans *  + c - '' ;
     return ans * sign ;
 }

 int n ;
 LL l[] , r[] ;
 LL la =  , ra = 10e9 +  ;

 void answer(){
     la =  , ra = 10e9 +  ;
     for(int i =  ; i <= n ; ++ i){
         la = max(la , l[i]) ;
         ra = min(ra , r[i]) ;
     }
 }

 int main(){
     n = read() ;
     LL ansl =  , ansr =  ;
     r[] = 10e9 +  ;
     l[] =  ;
     for(int i =  ; i <= n ; ++ i){
         l[i] = read() , r[i] = read() ;
     }
     answer() ;
     if(la > ra) {
         printf("%d",);
         return  ;
     }
     for(int i =  ; i <= n ; ++ i){
         if(l[i] == la){
             if(r[i] < r[ansl]) {
                 ansl = i ;
             }
         }
         if(r[i] == ra){
             if(l[i] > l[ansr]){
                 ansr = i ;
             }
         }
     }
     if(ansr == ansl){
         l[ansr] =  ;
         r[ansr] = 10e9 +  ;
         answer() ;
         printf("%ld",ra - la) ;
         return  ;
     }
     else {
         LL ii = l[ansr] ;
         LL ff = r[ansr] ;
         l[ansr] =  , r[ansr] = 10e9 +  ;
         answer() ;
         LL len = ra - la ;
         l[ansr] = ii , r[ansr] = ff ;
         l[ansl] =  , r[ansl] = 10e9 +  ;
         answer() ;
         len = max(len , ra - la) ;
         printf("%ld",len) ;
         return  ;
     }
 }