#include <bits/stdc++.h>
using namespace std;
#define int long long
constexpr int inf = 1e18;
constexpr int maxn = 2e5 + 5;
constexpr int mod = 998244353;

inline void solve()
{
  int n, m; cin >> n >> m;
  vector<string> s(n);
  for (auto &x : s) cin >> x;
  int mx = 0;
  for (int i = 0; i < m; i ++)
  {
    int cnt = 0;
    for (int j = 0; j < n; j ++) cnt += (s[j][i] == 'x');
    mx = max(mx, cnt);
  }
  cout << mx + 1 << "\n";
}

signed main()
{
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  solve();
  return 0;
}
/*
The details you should care:

*/