program SymbolicSequence; {.$APPTYPE CONSOLE}
var
    RndSeed: LongInt;

function MyRandom(Range: Integer): Integer;
var
    RDouble: Extended;
begin
    MyRandom := (RndSeed div 10000) mod Range;

    RDouble := RndSeed;
    RDouble := (RDouble * 3141592621 + 184421);
    RDouble := RDouble - $7FFFFFFF*Int(RDouble/$7FFFFFFF);
    RndSeed := Trunc(RDouble);
end;

var
    i: Integer;
begin
    RndSeed := 98586100;
    for i := 1 to 1000000 do
        Write(Chr(MyRandom(26) + Ord('a')));
    WriteLn;
end.

{ The tester program  }
program test; {$APPTYPE CONSOLE}
const
    OneCnt = 39000;
    TwoCnt = 1600;
    TriCnt = 97;

var
    i: Integer;
    S: String[4];
    Use1: array['a'..'z'] of Word;
    Use2: array['a'..'z', 'a'..'z'] of Word;
    Use3: array['a'..'z', 'a'..'z', 'a'..'z'] of Word;

    Ch: Char;
begin
    FillChar(Use1, SizeOf(Use1), 0);
    FillChar(Use2, SizeOf(Use2), 0);
    FillChar(Use3, SizeOf(Use3), 0);

    S := '123';
    Read(S[1], S[2], S[3]);
    Inc(Use1[S[1]]);
    Inc(Use1[S[2]]);
    Inc(Use1[S[3]]);

    Inc(Use2[S[1], S[2]]);
    Inc(Use2[S[2], S[3]]);

    Inc(Use3[S[1], S[2], S[3]]);

    for i := 4 to 1000000 do
    begin
        Read(Ch);
        if Ch in ['a'..'z'] then
        begin
            Delete(S, 1, 1);
            S := S + Ch;

            Inc(Use1[S[3]]);
            Inc(Use2[S[2], S[3]]);
            Inc(Use3[S[1], S[2], S[3]]);

            if Use1[S[3]] > OneCnt then
            begin
                WriteLn('Letter ', S[3], ' used more than ',
                          OneCnt, ' times!!!');
                Halt;
            end;

            if Use2[S[2], S[3]] > TwoCnt then
            begin
                WriteLn('Digraph ', S[2],S[3], ' used more than ',
                       TwoCnt, ' times!!!');
                Halt;
            end;

            if Use3[S[1], S[2], S[3]] > TriCnt then
            begin
                WriteLn('Trigraph ', S[1],S[2],S[3],
                        ' used more than ', TriCnt, ' times!!!');
                Halt;
            end;
        end else
        begin
            WriteLn('Error!!!');
            WriteLn('Not small latin letter at ', i);
            Halt;
        end;
    end;

    WriteLn('Ok');
end.

Writeln in the end is odd.

char s[1000005];

int p1[32];
int p2[32][32];
int p3[32][32][32];

bool ok()
{
    int i;
    for (i = 0; i < 1000000; i++)
        p1[s[i]]++;
    for (i = 1; i < 1000000; i++)
        p2[s[i-1]][s[i]]++;
    for (i = 2; i < 1000000; i++)
        p3[s[i-2]][s[i-1]][s[i]]++;

    for (i = 0; i < 26; i++)
        if (p1[i]>40000) return false;
    int j,k;
    for (i = 0; i < 26; i++)
        for (j = 0; j < 26; j++)
            if (p2[i][j]>2000) return false;
    for (i = 0; i < 26; i++)
        for (j = 0; j < 26; j++)
            for (k = 0; k < 26; k++)
                if (p3[i][j][k]>200) return false;
    return true;
}