I vs. V − I color–magnitude diagram for the 4614 stars from our sample of 4646 stars that have both I and V-band OGLE-III photometry. The spectral types are labeled as follows: O stars as black triangles, early-B stars as cyan circles, late-B stars as blue stars, and AFG-type stars as red inverted triangles. Only 1.3% of early-B type stars exhibit very red colors due to contamination.