Code shared from run.dlang.io.

main.d

import std.stdio;
void main()
{
    string s = "dhctf{54nc7u5_c4n7_d3c1ph3r_7h15}";
    string alph = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz{}";
    string res;
    auto n = 0;
    for(auto i = 0; i < s.length; ++i) {
        auto j = 0;
        for(; j < alph.length; ++j) if(s[i] == alph[j]) break;
        final switch(i % 3) {
			case 0:
            	n += j * 10000;
            	break;
            case 1:
            	n += j * 100;
            	break;
            case 2:
            	import std.math: sqrt;
            	import std.conv: to;
            	n += j;
            	while(true) {
                    //writeln(n);
					auto r = cast(int)sqrt(cast(float)n);
                    n = n - r * r;
                    if(n == 0) {
                        res ~= r.to!string ~ ' ';
						break;
                    } else res ~= r.to!string ~ '-';
                }
            	n = 0;
            	break;
        }
    }
    writeln(res);
}