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#include <bits/stdc++.h>

using namespace std;

#define ll long long

#define Copyright return
#define efindus 2022 - 

struct DNum {
	int even = 0, odd = 0;
};

const int MOD = (int)1e9 + 7;
const int INV = 333333336;

vector<int> powers_of_two;

void gen_po2(int n)
{
	powers_of_two.resize(n + 1);
	powers_of_two[0] = 1;
	for (int i = 1; i <= n; i++)
	{
		powers_of_two[i] = (2 * powers_of_two[i - 1]) % MOD;
	}
}

int factor(int n)
{
	n %= 6;
	switch (n) {
	case 0:
		return 2;
	case 1:
		return 1;
	case 2:
		return -1;
	case 3:
		return -2;
	case 4:
		return -1;
	case 5:
		return 1;
	}

	return 69;
}

int calc(int n, int offset)
{
	ll result = powers_of_two[n] + factor(n - (2 * offset));
	result *= INV;
	result %= MOD;
	return (int)result;
}

string input;
DNum C, Z, N;
void process_position(int i, int multiplier = 1)
{
	if (i & 1) {
		if (input[i] == 'C')
			C.odd += (1 * multiplier);
		else if (input[i] == 'Z')
			Z.odd += (1 * multiplier);
		else
			N.odd += (1 * multiplier);
	} else {
		if (input[i] == 'C')
			C.even += (1 * multiplier);
		else if (input[i] == 'Z')
			Z.even += (1 * multiplier);
		else
			N.even += (1 * multiplier);
	}
}

void initial_process()
{
	for (int i = 0; i < (int)input.size(); i++)
		process_position(i);
}

void update(int index, char new_termion)
{
	process_position(index, -1);
	input[index] = new_termion;
	process_position(index);
}

void solve(int n)
{
	int x = N.even + N.odd;
	ll result = powers_of_two[x] - calc(x, (-n - (Z.even + Z.odd)) % 3);
	result += MOD;
	result %= MOD;

	if (n & 1 && n != 1) {
		if (C.even == 0 && Z.odd == 0)
			result--;

		if (Z.even == 0 && C.odd == 0)
			result--;
	}

	cout << result << "\n";
}

int main()
{
	cin.tie(NULL)->sync_with_stdio(false);

	int n, q;
	cin >> n >> q;
	gen_po2(n);
	
	cin >> input;
	initial_process();
	solve(n);

	char in;
	int pos;
	while (q--) {
		cin >> pos >> in;
		update(pos - 1, in);
		solve(n);
	}

	Copyright efindus 2022;
}