# minor third
# +2 letters (the third letter) with exactly 1 half step between

# c,e- c+,e d,f
c  c+ d
e- e  f

# d+,f+ e,g f,g+
d+ e  f
f+ g  g+

# f+,a g,a+ g+,b
f+ g  g+
a  a+ b

# a,c a+,c+ b,d
a  a+ b
c  c+ d