import sys

n,m,k = map(int,input().split())

S = [input() for i in range(n)]
dic = {}

for i in range(n):

    for j in range(m):

        a = []

        for x in range(k):

            a.append( S[i][j*k + x] )
            
        a = "".join(a)

        if a not in dic:
            dic[a] = []
        dic[a].append( (i,j) )

for a in dic:
    if len(dic[a]) == 1:
        ij = dic[a][0]
        print (ij[0] + 1 , ij[1]+1)
        sys.exit()