Complete residue system

A Complete residue system modulo $n$ is a set of integers which satisfy the following condition: Every integer is congruent to a unique member of the set modulo $n$.

In other words, the set contains exactly one member of each residue class.

Examples

$\{1,2,3\}$, $\{4,5,6\}$, and $\{9,17,85\}$ are all Complete residue systems $\pmod{3}$.

$\{k,k+1,k+2,k+3,\ldots,k+m-1\}$ is a complete residue system $\pmod{m}$, for any integer $k$ and positive integer $m$. Basically, any consecutive string of $m$ integers forms a complete residue system $\pmod{m}$.