function [crossboard] = crossboard2(M,N,C,F)
L1 = floor(M/C);
L2 = floor(N/F);
zeros_cell = ones(L2, L1, 'single')*(-1);
ones_cell = ones(L2, L1, 'single');
intern_columns_extrem_rows = repmat(zeros_cell, [1 C-2]);
extrem_rows = [ones_cell intern_columns_extrem_rows ones_cell];
intern_columns_extrem_rows = repmat(ones_cell, [1 C-2]);
intern_rows = [zeros_cell intern_columns_extrem_rows zeros_cell];
intern_crossboard = repmat(intern_rows', [1 F-2]);
crossboard = [extrem_rows; intern_crossboard' ;extrem_rows];
end