public static void main ( String args [ ] ) {
  FastReader input = new FastReader ( ) ;
  PrintWriter out = new PrintWriter ( System . out ) ;
  int T = input . nextInt ( ) ;
  while ( T -- > 0 ) {
    int n = input . nextInt ( ) ;
    String s = input . next ( ) ;
    int l = - 1 ;
    for ( int i = 0 ;
    i < n ;
    i ++ ) {
      if ( s . charAt ( i ) == '1' ) {
        l = i ;
        break ;
      }
    }
    if ( l == - 1 ) {
      out . println ( n ) ;
    }
    else {
      int r = - 1 ;
      for ( int i = n - 1 ;
      i >= 0 ;
      i -- ) {
        if ( s . charAt ( i ) == '1' ) {
          r = i ;
          break ;
        }
      }
      int d1 = r + 1 ;
      int d2 = n - l ;
      out . println ( Math . max ( d1 * 2 , d2 * 2 ) ) ;
    }
  }
  out . close ( ) ;
}

public static void main ( String args [ ] ) { FastReader input = new FastReader ( ) ; PrintWriter out = new PrintWriter ( System . out ) ; int T = input . nextInt ( ) ; while ( T -- > 0 ) { int n = input . nextInt ( ) ; String s = input . next ( ) ; int l = - 1 ; for ( int i = 0 ; i < n ; i ++ ) { if ( s . charAt ( i ) == '1' ) { l = i ; break ; } } if ( l == - 1 ) { out . println ( n ) ; } else { int r = - 1 ; for ( int i = n - 1 ; i >= 0 ; i -- ) { if ( s . charAt ( i ) == '1' ) { r = i ; break ; } } int d1 = r + 1 ; int d2 = n - l ; out . println ( Math . max ( d1 * 2 , d2 * 2 ) ) ; } } out . close ( ) ; }
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