#include <bits/stdc++.h>
using namespace std;

template<class T> istream& operator >> (istream& is, vector<T>& vec) {
    for(T& x : vec) is >> x;
    return is;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int h, w;
    cin >> h >> w;
    vector<string> A(h), B(h);
    cin >> A >> B;
    int cnt1 = 0, cnt2 = 0;
    for(int y = 0; y < h; y++){
        for(int x = 0; x < w; x++){
            cnt1 += A[y][x] != B[y][x];
            cnt2 += A[h - 1 - y][w - 1 - x] != B[y][x];
        }
    }
    double ans = 0, p = 1, div = 1;
    for(int i = 0; i < 100; i++){
        if (i % 2 == 0 && cnt1 == h * w){
            ans += p * (1 - div) * (i + 1);
            p *= div;
        }
        else if(i % 2 == 1 && cnt2 == h * w){
            ans += p * (1 - div) * (i + 1);
            p *= div;
        }
        div /= 2;
    }
    cout << fixed << setprecision(15) << ans << '\n';
}