function r=f(s,t)
s=lower(s);t=lower(t);u=unique([s t]);r=sum(abs(histc(s,u)-histc(t,u)));

end %// needed in online compiler only

input1 = 'This is not exactly like Levenshtein distance,';
input2 = 'but you''ll notice it is quite similar.';
f(input1, input2)