var n,i,j,s,r:integer;
    c:char;
    f,g:text;

function pu(x:integer):integer;
begin
case x of
  0: pu:=0;
  1: pu:=1;
  2: pu:=5;
  3: pu:=2;
  4: pu:=8;
  5: pu:=3;
  6: pu:=9;
  7: pu:=2;
  8: pu:=8;
  9: pu:=7;
end;
end;

begin
  assign(f,'cifra.in');
  assign(g,'cifra.out');
  reset(f);
  rewrite(g);
  readln(f,n);
  read(n);
  for i:=1 to n do
    begin
      s:=0;
      repeat
        read(f,c);
        r:=ord(c)-48;
        read(r);
        for j:=1 to r do
          s:=(s mod 10)+pu(j);
      until(eoln(f));
      readln(f);
      writeln(g,s mod 10);
    end;
  close(g);
end.