function y = modulo5(x)
x = char(x);
x = upper(x);
for i = 1:length(x)
    switch x(i)
        case 'I', y(i) = 0;
        case 'A', y(i) = 1;
        case 'G', y(i) = 2;
        case 'C', y(i) = 3;
        case 'U', y(i) = 4;
    end
end
y = mod(sum(y),5);