who can help me? I WA on #7.Why?

here is my program:
var
  a:array[1..1000]of longint;
  b:array[1..1000,1..1000]of boolean;
  n,i,j,x,y,m:longint;
  c:boolean;
  function find(x,y:longint):boolean;
    var
      i:longint;
    begin
      if b[x,y] then exit(false);
      for i:=1 to m do
        if (b[a[i],x])and(b[a[i],y])then
          begin
            b[x,y]:=true;b[y,x]:=true;
            exit(false);
          end;
      exit(true);
    end;

begin
  while not seekeof do
    begin
      readln(x,y);
      b[x,x]:=true;b[y,y]:=true;
      b[x,y]:=true;b[y,x]:=true;

      c:=true;
      for j:=1 to m do
        if a[m]=x then begin c:=false;break;end;
      if c then
        begin
          inc(m);a[m]:=x;
          for i:=1 to m do
            if find(a[i],x) then
              begin
                writeln(0);halt;
              end;
        end;

      c:=true;
      for j:=1 to m do
        if a[m]=y then begin c:=false;break;end;
      if c then
        begin
          inc(m);a[m]:=y;
          for i:=1 to m do
            if find(a[i],y) then
              begin
                writeln(0);halt;
              end;
        end;
    end;
  writeln(1);
end.

Pls check for the following case:

5 6
5 8
5 9
6 7
8 9
9 10

Answer should be 1

Test 7 has invert vertexes.
10 1
1 2

asn: 1

I have many times WA, because my programm doesnt check it.