import sys n,m,k=map(int,input().split()) table=[] for i in range(n): table.append(list(input())) result=[] for j in range(m): middle=[] for w in range(n): middle.append(table[w][j]) # print(middle) we=0 while we<n: if middle[we]=='o': length=0 while we<n and middle[we]=='o': we+=1 length+=1 result.append(length) else: we+=1 result.sort(reverse=True) total = 0 remaining = k for length in result: if remaining <= 0: break #判断连续染色数,看是length全染还是只染剩余remaining use = min(length, remaining) if use >= 2: total += use - 1 remaining -= use print(total)