#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001
bool check(vector<string> x,vector<string> y){
	rep(i,x.size()){
		rep(j,x[i].size()){
			if(x[i][j]==y[i][j])return false;
		}
	}
	return true;
}
int main(){
	
	int h,w;
	cin>>h>>w;
	vector<string> s(h),t(h);
	rep(i,h)cin>>s[i];
	rep(i,h)cin>>t[i];
	bool f0 = check(s,t);
	rep(i,h){
		reverse(t[i].begin(),t[i].end());
	}
	reverse(t.begin(),t.end());
	bool f1 = check(s,t);
	double ans = 0,cp = 1;
	rep(i,5000000){
		double p = 0;
		if(i%2==0&&f0)p = 1-pow(2.0,-i);
		if(i%2==1&&f1)p = 1-pow(2.0,-i);
		ans += cp*p*(i+1);
		cp *= 1-p;
	}
	cout<<fixed<<setprecision(10)<<ans<<endl;
	
    return 0;
}