var f,g:text;
n:integer;
procedure kt_ndl;
begin
Assign(f,'DE20.INP'); reset(f);
Assign(g,'DE20.OUT'); rewrite(g);
readln(f,n);
end;
function ktnt(k:byte):boolean;
var l:byte;
begin
ktnt:=false;
if k<2 then exit;
for l:=2 to trunc(sqrt(k)) do
if k mod l=0 then exit;
ktnt:=true;
end;
procedure xuly;
var t,i:byte;
begin
t:=0;
while n>0 do
begin
i:=n mod 10;
if ktnt(i) then t:=t+i;
n:=n div 10;
end;
write(g,t);
end;
BEGIN
kt_ndl; xuly;
close(f); close(g);
END.
