How to solve the error

Please help me to execute the following code
clear all;
clc;
N_UE = [2 4 6 8 10];  % number of users
N_SC = [20 30 40 50 60]; % number of subcarriers
for t = 1:length(N_UE)
  for r = 1:length(N_SC)
        G=rand(N_UE(t),N_SC(r))% random selection of users and subcarriers
    % subcarrier allocation to users%
    siz = size(G);
    idx = sub2ind(siz, randi([1,N_UE(t)], 1, siz(2)),1:siz(2));
    C = zeros(siz);
    C(idx) = G(idx);
        s = randperm(N_UE(t))
% s = randperm(length(N_UE))
numGroups = 5; % Need to divide s up into 5 groups
divisions = sort(randperm(C, numGroups) , 'ascend')
% divisions = sort(randperm(numUsers-2, numGroups-1) + 1, 'ascend')
divisions = [0, divisions, C]
% Create cell array with random number of users in each groups
groups = cell(1, numGroups);
for k = 1 : numGroups
  indexes = divisions(k)+1:divisions(k+1);
  % Assign users to the kth group:
  usersInThisGroups = length(indexes);
  fprintf('Assigning %d users (indexes %d to %d) to group %d.\n', ...
    usersInThisGroups, divisions(k)+1,divisions(k+1), k);
  groups{k} = s(indexes);
end
celldisp(groups); % D

  end
end

as i am getting Error using randperm Inputs must be nonnegative scalar integers.

Error in two (line 25) divisions = sort(randperm(C,numGroups) ,'ascend')

[ANKUR KUMAR]

Is this your homework problem? Prog for the same homework question can be found here: https://in.mathworks.com/matlabcentral/answers/373858-could-anyone-tell-me-how-to-execute-the-following-code