program t1208;
const p=20;
var s,s1:array[1..p,1..3]of string[20];
    a:string;
    n,i,j,k,st,t,max,m,i1,j1:integer;
begin
     readln(n);
     for i:=1 to p do
         for j:=1 to 3 do s[i,j]:='';
     for i:=1 to n do
         begin
         readln(a);
         t:=1; st:=1;
         for j:=1 to length(a) do
         if a[j]=' ' then
            begin
            for k:=st to j-1 do s[i,t]:=s[i,t]+a[k];
            st:=j+1;
            inc(t);
            end
         else if j=length(a) then for k:=st to j do s[i,t]:=s[i,t]+a
[k];
         end;
     if n=1 then begin writeln(1); halt; end;
     m:=0;
     for i:=1 to n do begin
         if max>m then m:=max;
         max:=0;
         s1:=s;
         for i1:=1 to n do for j1:=1 to 3 do
             begin
             if (s1[i1,j1]=s[i,1])and(i1<>i) then s1[i1,j1]:='';
             if (s1[i1,j1]=s[i,2])and(i1<>i) then s1[i1,j1]:='';
             if (s1[i1,j1]=s[i,3])and(i1<>i) then s1[i1,j1]:='';
             end;
         for j:=1 to n do
             if (s1[j,1]<>'')and(s1[j,2]<>'')and(s1[j,3]<>'')
             then begin
                  inc(max);
                  for i1:=1 to n do for j1:=1 to 3 do
                      begin
                      if s1[i1,j1]=s[j,1] then s1[i1,j1]:='';
                      if s1[i1,j1]=s[j,2] then s1[i1,j1]:='';
                      if s1[i1,j1]=s[j,3] then s1[i1,j1]:='';
                      end;
                  end;
         end;
     writeln(m);
end.

Try this:

6
a b c
b h j
c t y
aa bb cc
bb hh jj
cc tt yy

Output should be 4, but your pg output 3.