Group ${1, -1, i, -i}$ Cordial Labeling of sum of $C_n$ and $K_m$ for some $m$

Let G be a (p,q) graph and A be a group. We denote the order of an element a in A by o(a).  Let f:V(G)rightarrow A be a function. For each edge uv assign the label 1 if (o(f(u)),o(f(v)))=1 or 0 otherwise. f is called a group A Cordial labeling if |v_f(a)-v_f(b)| leq 1 and |e_f(0)- e_f(1)|leq 1, where v_f(x) and e_f(n) respectively denote the number of vertices labelled with an element x and number of edges labelled with n (n=0,1). A graph which admits a group A Cordial labeling is called a group A Cordial graph. In this paper we define group {1 ,-1 ,i ,-i} Cordial graphs and characterize the graphs C_n + K_m (2 leq m leq 5) that  are group {1 ,-1 ,i ,-i} Cordial.the formula is not displayed correctly!