Program exer (input,output);
var i,N,p,c:integer;
begin
readln (N);
i:=1;
c:=i mod 10;
p:=0;
while (i<=N)) do
begin
if (i=2) or (i=5) or (c=1) or (c=3) or (c=7) or (c=9) and
begin
p:=p+1;
i:=i+1;
c:= i mod 10;
end;
end;
writeln (p);
end.
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