Brain16 useful large

# A brain16's useful decimal is its shortest form even when large (check claude, seed 25294): 2^63
# as a brain16 is 9220000000000000000, which fits an int64, not its stored 9223372036854775808.
MAIN {
    let 'i': int64 = 9223372036854775803;
    let 'b' := to.brain16['i'];
    let 'd' := to.useful.deci64['b'];
    let 'n' := to.int64['d'] otherwise -1;
    std::print.useful['b', " ", 'd', " ", 'n', newln];
}