var     st,st1,st2,st3,st4      :string;
        x,y,z,v,k               :array[1..2] of extended;
        r,kc                    :extended;

procedure doc(var st :string; var t :extended);
begin
  t := 0;
  while ( st[1] >= '0') and ( st[1] <= '9' ) do
  begin  t := t * 10 + ord( st[1] ) - 48;
         delete(st,1,1);
  end;
  delete(st,1,1);
end;


procedure doc1(var st :string; var t :extended);
var    x,y,z       :extended;
begin
  while ( st[1] < '0' ) or ( st[1] > '9' ) do delete(st,1,1);
  doc(st, x); doc(st,y); doc(st, z);

  t := x + y/60 + z/3600;
  t := t * pi / 180;
  if ( pos('SL',st) > 0 ) or ( pos('WL',st) > 0 )
      then t := -t;
end;


procedure input;
begin
  readln( st);
  readln( st);
  readln( st);
  readln( st1);
  readln( st2);
  readln( st);
  readln( st3);
  readln( st4);

  doc1(st1, v[1]); doc1(st2, k[1]);
  doc1(st3, v[2]); doc1(st4, k[2]);
end;


procedure tinh_toa_do;
begin
  r := 6875/2;
  x[1] := r * sin( v[1] );
  y[1] := r * cos( v[1] ) * sin( k[1] );
  z[1] := r * cos( v[1] ) * cos( k[1] );

  x[2] := r * sin( v[2] );
  y[2] := r * cos( v[2] ) * sin( k[2] );
  z[2] := r * cos( v[2] ) * cos( k[2] );
end;



procedure tinh_khoang_cach;
var    canh,co,goc         :extended;
begin
  canh := sqrt( sqr( x[1] - x[2] ) + sqr( y[1] - y[2] ) +
                sqr( z[1] - z[2] ) );
  co  := ( 2*sqr(r) - sqr(canh) ) / ( 2 * sqr(r) );

  if co = 0 then goc := pi/2
            else goc := arctan( sqrt( 1/sqr(co) - 1 ) );

  kc := r * goc;
end;


procedure solve;
begin
  tinh_toa_do;
  tinh_khoang_cach;
end;


procedure out;
begin
  writeln('The distance to the iceberg: ',kc:0:2,' miles.');
  if kc < 99.95 then writeln('DANGER!');
end;


begin
  input;
  solve;
  out;
end.

maybe : you div zero , or sqrt(negative number)



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