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#include <bits/stdc++.h>

using namespace std;


unsigned long long PRIME = 1e9+7;
unsigned long long INVERSE = 333333336;

long long power(long long x, unsigned int y, int p)
{
    long long res = 1; 
    x = x % p;  
    if (x == 0) return 0; // In case x is divisible by p;
 
    while (y > 0)
    {
        if (y & 1)
            res = (res*x) % p;
        y = y>>1;
        x = (x*x) % p;
    }
    return res;
}

unsigned long long binom_sum(long long n, long long p){
    unsigned long long result = (unsigned long long) (
        power(2, n, PRIME) 
        + round(cos(M_PI*(n - 2*p)/3) 
        + (n % 2 ? -1 : 1) * cos(M_PI*2*(n - 2*p)/3))
        + PRIME
    ) % PRIME;
    result *= INVERSE;
    return result % PRIME;
}


unsigned long long solve(vector<int> dist, vector<int> pos_dist) {
    int length = dist[0] + dist[1] + dist[2];
    unsigned long long counter = power(2, dist[2], PRIME);
    counter = (counter + PRIME - binom_sum(dist[2], ((2*length - 4*dist[1]))%3))%PRIME;

    if(length % 2 == 1 && pos_dist[0] == 0 && pos_dist[3] == 0)
        counter--;
    if(length % 2 == 1 && pos_dist[1] == 0 && pos_dist[2] == 0)
        counter--;
    
    return counter;
}   


int main() {
    std::ios_base::sync_with_stdio(false);

    int n, q;
    cin >> n >> q;

    string chain;
    cin >> chain;

    vector<int> dist(3);
    vector<int> pos_dist(4);

    dist[0] = 0; dist[1] = 0; dist[1] = 0;
    pos_dist[0] = 0; pos_dist[1] = 0; pos_dist[2] = 0; pos_dist[3] = 0;
    
    for(int i = 0; i < chain.size(); i++) {
        if(chain[i] == 'Z'){
            pos_dist[i%2]++;
            dist[0]++;
        }
        else if (chain[i] == 'C'){
            pos_dist[2 + i%2]++;
            dist[1]++;
        }
        else
            dist[2]++;   
    }
    cout << solve(dist, pos_dist) << endl;
    for(int i = 0; i < q; i++){
        int idx;
        char new_char;
        cin >> idx >> new_char;
        idx--;
        if(chain[idx] != new_char) {
            if(chain[idx] == 'Z'){
                pos_dist[idx%2]--;
                dist[0]--;
            }
            else if (chain[idx] == 'C'){
                pos_dist[2 + idx%2]--;
                dist[1]--;
            }
            else
                dist[2]--; 

            chain[idx] = new_char;
            if(new_char == 'Z'){
                pos_dist[idx%2]++;
                dist[0]++;
            }
            else if (new_char == 'C'){
                pos_dist[2 + idx%2]++;
                dist[1]++;
            }
            else
                dist[2]++;  

        }

        cout << solve(dist, pos_dist) << endl;
    }

    return 0;
}