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#include <iostream>

using namespace std;

using ll = long long;

constexpr ll mod = 1000000007;

ll thirds[3][200200]; 
ll pot[200200];

void init() {
	pot[0] = 1;
	for(int i = 1; i < 200100; i++) {
		pot[i] = (pot[i - 1] * 2) % mod;
	}
	thirds[0][0] = 1;
	for(int i = 1; i < 200100; i++) {
		for(int j = 0; j < 3; j++) {
			thirds[j][i] = (pot[i - 1] - thirds[(j + 1) % 3][i - 1] + mod) % mod;
		}
	}
}

int whatLetter(char c) {
	switch (c) {
	case 'C':
		return 0;
	case 'Z':
		return 1;
	case 'N':
		return 2;
	default:
		return 2;
	}
}

string s;
int n, q;
int onParity[2][3];
int il[3];

ll result() {
	if (n == 1) return 1;
	ll wyn = pot[il[2]];
	//cout << " " << wyn;
	if (n % 2 == 1) {
		if (!onParity[0][0] && !onParity[1][1]) wyn--;
		if (!onParity[1][0] && !onParity[0][1]) wyn--;
	}
	//cout << " " << wyn;
	wyn = wyn - thirds[(((il[2] + il[1] - il[0]) * 2) % 3 + 3) % 3][il[2]];
	//cout << " " << wyn;
	wyn = (wyn % mod + mod) % mod;
	//cout << " " << wyn;
	//cout << "\n";
	return wyn;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	init();
	cin >> n >> q;
	cin >> s;
	for (int i = 0; i < n; i++) {
		int what = whatLetter(s[i]);
		onParity[i % 2][what]++;
		il[what]++;
	}
	cout << result() << "\n";
	int a;
	string zm;
	for (int i = 0; i < q; i++) {
		cin >> a >> zm;
		a--;
		int old = whatLetter(s[a]), news = whatLetter(zm[0]);
		s[a] = zm[0];
		onParity[a % 2][old]--;
		onParity[a % 2][news]++;
		il[old]--;
		il[news]++;
		cout << result() << "\n";
	}
}