#include <cstdio>
#include <stack>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <functional>
#include <cstring>
#include <algorithm>
#include <cctype>
#include <string>
#include <map>
#include <cmath>
#define LL long long
#define SZ(x) (int)x.size()
#define Lowbit(x) ((x) & (-x))
#define MP(a, b) make_pair(a, b)
#define MS(arr, num) memset(arr, num, sizeof(arr))
#define PB push_back
#define F first
#define S second
#define ROP freopen("input.txt", "r", stdin);
#define MID(a, b) (a + ((b - a) >> 1))
#define LC rt << 1, l, mid
#define RC rt << 1|1, mid + 1, r
#define LRT rt << 1
#define RRT rt << 1|1
#define BitCount(x) __builtin_popcount(x)
const double PI = acos(-1.0);
const int INF = 0x3f3f3f3f;
using namespace std;
const int MAXN = 10000 + 10;
const int MOD = 1e9 + 7;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
 
typedef pair<int, int> pii;
typedef vector<int>::iterator viti;
typedef vector<pii>::iterator vitii;
 
int next[MAXN], row, col;
char str[MAXN][80];
 
int GetFailc(int n)
{
    int i = 0, j = -1;
    next[0] = -1;
    while (i < col)
    {
        if (j == -1 || str[n][i] == str[n][j])
        {
            i++; j++;
            next[i] = j;
        }
        else j = next[j];
    }
    return i - next[i];
}
 
int GetFailr(int n)
{
    int i = 0, j = -1;
    next[0] = -1;
    while (i < row)
    {
        if (j == -1 || str[i][n] == str[j][n])
        {
            i++, j++;
            next[i] = j;
        }
        else j = next[j];
    }
    return i - next[i];
}
 
int LCM(int a, int b)
{
    return a * b / __gcd(a, b);
}
 
int main()
{
    //ROP;
    int i, j;
    scanf("%d%d", &row, &col);
    int ansR = 1, ansC = 1;
    for (i = 0; i < row; i++) scanf("%s", str[i]);
    for (i = 0; i < row; i++)
    {
        ansR = LCM(ansR, GetFailc(i));
        if (ansR > col)
        {
            ansR = col;
            break;
        }
    }
    for (i = 0; i < col; i++)
    {
        ansC = LCM(ansC, GetFailr(i));
        if (ansC > row)
        {
            ansC = row;
            break;
        }
    }
    printf("%d\n", ansC * ansR);
    return 0;
}