n,m,k=input().split(' ') n,m,k=int(n),int(m),int(k) matr=[] for i in range(n): l=list(input()) matr.append(l) count_l=[] for col in range(m): count=1 current=matr[0][col] for row in range(1,n): if matr[row][col]==current: count+=1 else: if current=='o': count_l.append(count) current=matr[row][col] count=1 if current == 'o': count_l.append(count) score=0 all=0 count_l.sort(reverse=True) for i in range(len(count_l)): if count_l[i]==1: break all+=count_l[i] if all>k: # last=count_l[i] score=score+count_l[i]-(all-k)-1 break score=score+count_l[i]-1 if all==k: break print(score)