could anyone help me to run the following code without error

A=[ 1 2 3 4 5;
    11 12 13 14 15;
    6 7 8 9 10;
    21 22 23 24 25;
    26 27 28 29 30];
B=[0 0 41 0 0;
    45 0 0 0 0;
    0 43 0 0 0;
    0 0 0 42 0;
    0 0 0 0 44];
a=1:5
for N=2:4 
    c=randsample(a,N)
    B_part=B(c,:)
    non_0=sum(B_part)
    [~,idx]=find(ismember(a,c))
    if N==4
    else
    a(idx)=[]
    end
end
 C_after_step_1=cluster_rows(B_part)

calling function
function C=cluster_rows(B_part)
extract the parts of the matrices
A_part=A(rows,:);
B_part=B(rows,:);
non_0=repmat(non_0,length(rows),1);
C=B;
C_part=B_part;
C_part(non_0 & C_part==0)=A_part(non_0 & C_part==0);
C(rows,:)=C_part;
end