lets take an example:
There is K boxes (k=5). And N objects (N=6). pigeonhole-principle says that at least one Box contain r objects (r=2).Then
ceilOf(N/K) ≥ r
ceilOf(5/4) ≥ r
2 ≥ r // r=2 which is true
ceilOf(N/K) can be greater than r Here we take only least amount of objects