program DAGIAC;
var n: int64;
fi, fo: text;
begin
assign(fi, 'DAGIAC.inp'); reset(fi);
assign(fo, 'DAGIAC.out'); rewrite(fo);
read(fi, n);
write(fo, n * (n - 1) * (n - 2) * (n - 3) div (1 * 2 * 3 * 4));
close(fi);
close(fo);
end.
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