import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.math,
       std.algorithm;

void main()
{
    auto input = readln.split;
    auto W = input[0].to!int, H = input[1].to!int;
    auto C = input[2];

    auto cur = (C == "B" ? 0 : 1);
    auto color = ["B", "W"].cycle;
    iota(H)
        .tee!(a => writeln)
        .each!(h => iota(W)
               .each!(w => color[cur++].write));
}