These letters are above the larger letters, see here, and describe the start of the plague in the village.
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The above words are in their original: Primula pestis i (n) m ter ccc fuit l minus uno
and in translation: Just the first plague was in 1000, 300 and 50 minus 1
Note the interesting form used for the year of 1349. The letters in brackets is missing from the wall.