var n,i,tong: integer;
begin
readln(n);
tong:=0;
if (n mod 5 = 0) then
begin
tong:=tong+(n div 5);
writeln(tong);
end
else
begin
tong:=tong+(((n mod 5) div 3) + 1);
writeln(tong);
end;
end.
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