import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.math,
       std.algorithm;

void main()
{
    auto N = readln.strip.to!int;
    auto A = stdin.byLineCopy.map!split.array;

    int[] ans;
    foreach (j; 0 .. N)
    {
        int count;
        foreach (i; 0 .. N)
        {
            if (A[i][j] == "nyanpass")
                count++;
        }
        if (count == N - 1)
            ans ~= j + 1;
    }
    (ans.length == 1 ? ans.front : -1).writeln;
}