#include <stdio.h>
#include <algorithm>

using namespace std;

#define NMAX 1111

char A[NMAX][NMAX];
int M, N;

void ReadInput() {
	scanf("%d %d", &M, &N);
	for (int i = 0; i < M; ++i) {
		scanf("%s", &A[i][0]);
		for (int j = 0; j < N; ++j)
			if (A[i][j] == 'R') A[i][j] = 0;
			else A[i][j] = 1;
	}
}

int Solve(int parity) {
	int ans = 0;
	for (int i = 0; i < M; ++i)
		for (int j = 0; j < N; ++j) {
			if (((i + j) & 1) == (A[i][j] ^ parity)) continue;
			if (A[i][j] == 0) ans += 5;
			else ans += 3;
		}
	return ans;
}

int main() {
	int T;
	scanf("%d", &T);
	while (T--) {
		ReadInput();
		printf("%d\n", min(Solve(0), Solve(1)));
	}
	return 0;
}