n = gets.to_i
array = Array.new(n, 1)
for i in 0..n-1 do
    a = gets.split()
    for j in 0..n-1 do
        if (a[j] != "nyanpass" && a[j] != "-")
            array[j] = 0
        end
    end
end

ans = -1
for i in 0..n-1 do
    if (array[i] == 1)
        if (ans != -1)
            p -1
            exit
        else
            ans = i+1
        end
    end
end
p ans