program ount_7 (input, output);
var n, n1, n2, metr : integer;
begin
readln(n);
n1:=(n mod 10);
n2:=(n div 10);
metr:=0;
if (n1=7) then metr:=metr+1;
if (n2=7) then metr:=metr+1;
writeln(metr)
end.