#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
using namespace std;

using ll = long long;
const int INF = 1e9;
const ll inf = 1LL<<62;

void solve() {
  int n, m; cin >> n >> m;
  vector<string> s(n);
  for (int i=0; i<n; i++) cin >> s[i];
  vector<int> cnt(m);
  for (int i=0; i<n; i++) for (int j=0; j<m; j++) cnt[j] += (s[i][j] == 'x');
  cout << *max_element(cnt.begin(), cnt.end()) + 1 << '\n';
}

int main() {
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  // int t; cin >> t;
  /*while (t--)*/ solve();
}