The restricted sumsets in finite abelian groups

Suppose that k≥ 2 and A is a non-empty subset of a finite abelian group G with $|G|>1$. Then the cardinality of the restricted sumset k^ A:=₁+⋯+aₖ:\,a₁,…,aₖ∈ A,\ aᵢ≠ aⱼ for i≠ j\ is at least min(G), k|A|-k²+1\, where $p(G)$ denotes the least prime divisor of $|G|$.