let nm = readLine()!.split(separator: " ").map{Int($0)!}
let (n,m) = (nm[0],nm[1])
var arr = [[String]]()
for i in 1...n{
    let ar = readLine()!.map{String($0)}
    arr.append(ar)
}
var ans = 0
for i in 0..<m{
    var cnt = 0
    for j in 0..<n{
        if arr[j][i] == "x"{
            cnt += 1
        }
    }
    ans = max(ans,cnt+1)
}
print(ans)