void main()

{

    import std.range;

    import std.stdio: write, writeln, writef, writefln;

    import std.algorithm.sorting : sort;

    size_t[] lines  = [20, 1755, 1756, 1757, 1798, 1824, 1825, 1839, 1840];

    size_t search = 21;

    auto r = assumeSorted(lines);

    auto l = r.lowerBound(search);

    auto e = r.equalRange(search);

    auto u = r.upperBound(search);

    auto f = r.trisect(search);

    writeln(l);

    writeln(f[0]);

​

    writeln(e);

    writeln(f[1]);

​

    writeln(u);

    writeln(f[2]);

}