let murabito = Int(readLine()!)!

var map = [[String]]()

for i in 0..<murabito {
        map.append(readLine()!.split(separator:" ").map(String.init))
}

var ans:Int? = nil
for i in 0..<murabito {
    var isNyan = true
    for j in 0..<murabito {
        if(map[j][i]=="nyanpass" || map[j][i] == "-") {
            
        } else {
            isNyan = false
            break
        }
    }
    if(isNyan) {
        if(ans == nil) {
            ans = i+1
        } else {
            ans = nil
            break
        }
    }
}

if(ans == nil) {
    print(-1)
} else {
    print(ans!)
}