The melody of Un-Thinkable by Alicia Keys runs 477 notes across 53 bars, 4:11 long in Bm at 86 beats per minute. The tab sits low on the neck, mostly under the fourth fret, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? Un-Thinkable chords and lyrics.