#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using VS = vector<string>;
using P = pair<ll,ll>;
using VP = vector<P>;
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define out(x) cout << x << endl
#define dout(x) cout << fixed << setprecision(10) << x << endl;
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x.size())
#define re0 return 0
#define pcnt __builtin_popcount
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//const int INF = 1001001001;
const ll INF = 1e18;
//using mint = modint1000000007;
//using mint = modint998244353;
int di[4] = {0,-1,0,1};
int dj[4] = {-1,0,1,0};

int main(){
    int n,m;
    cin >> n >> m;
    vector<string> s(n);
    rep(i,n) cin >> s[i];
    ll ans = 0;
    rep(j,m){
        ll cnt = 0;
        rep(i,n) if(s[i][j] == 'x') cnt++;
        chmax(ans,cnt);
    }
    out(ans+1);
}