import java.util.* ;
public class Main
{
public static void main
( String [ ] args
) { Scanner sc
= new Scanner
( System .
in ) ;
int n = sc.nextInt ( ) ;
int [ ] nums = new int [ n] ;
int [ ] prefixsum = new int [ n] ;
int [ ] suffixsum = new int [ n] ;
for ( int i = 0 ; i < n; i++ ) {
nums[ i] = sc.nextInt ( ) ;
}
int k = sc.nextInt ( ) ;
prefixsum[ 0 ] = nums[ 0 ] ;
for ( int i = 1 ; i < n; i++ ) {
prefixsum[ i] = prefixsum[ i- 1 ] + nums[ i] ;
}
suffixsum[ n- 1 ] = nums[ n- 1 ] ;
for ( int i = n- 2 ; i >= 0 ; i-- ) {
suffixsum[ i] = suffixsum[ i+ 1 ] + nums[ i] ;
}
for ( int i = - 1 ; i < k; i++ ) {
int j = n + i + 1 - k;
int sum;
if ( i == - 1 ) {
sum = suffixsum[ j] ;
maxsum
= Math .
max ( maxsum, sum
) ; }
else if ( j == n) {
sum = prefixsum[ i] ;
maxsum
= Math .
max ( maxsum, sum
) ; }
else if ( j > n- 1 ) {
break ;
}
else {
sum = prefixsum[ i] + suffixsum[ j] ;
maxsum
= Math .
max ( maxsum, sum
) ; }
}
}
}
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