template<typename T>
class matrix
{
public:
    static const size_t STANDART_SIZE = 2;
    matrix(void)
        : ver_size(STANDART_SIZE), hor_size(STANDART_SIZE), data(new T*[STANDART_SIZE])
    {
        for(size_t i = 0; i < ver_size; i++)
            data[i] = new T[hor_size];
    }
    matrix(size_t v_size, size_t h_size)
        : ver_size(v_size), hor_size(h_size), data(new T*[v_size])
    {
        for(size_t i = 0; i < ver_size; i++)
            data[i] = new T[hor_size];
    }
    ~matrix(void)
    {
        for(size_t i = 0; i < ver_size; i++)
            delete[] data[i];
        delete[] data;
    }
    inline size_t get_vertical_size(void) const
    {
        return ver_size;
    }
    inline size_t get_horizontal_size(void) const
    {
        return hor_size;
    }
    inline const T*& operator[](size_t index) const
    {
        return data[index];
    }
    inline T*& operator[](size_t index)
    {
        return data[index];
    }
    size_t longest_series_ver(void) const
    {
        size_t k, l(0), max(0);
        for(size_t i = 0; i < hor_size; i++)
        {
            k = 0;
            for(size_t j = 0; j < ver_size-1; j++)
            {            
                if(data[j][i] == data[j+1][i])
                    k++;
                else
                    k = 0;
                if(k > l)
                {
                    max = i;
                    l = k;
                }
            }    
        }
        return max;
    }
protected:
    size_t ver_size;
    size_t hor_size;
    T** data;
};

#include <iostream>
using namespace std;

int main(void)
{
    size_t n, m;
    cin >> n >> m;
    matrix<size_t> ar(n, m);
    for(size_t i = 0; i < n; i++)
        for(size_t j = 0; j < m; j++)
            cin >> ar[i][j];
    cout << ar.longest_series_ver()+1 << endl;
    system("pause");
    return 0;
}