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#include <iostream>
using namespace std;

long long pref0[200007];
long long pref12[200007];
long long pw2[200007];

long long m = (long long) 1000000007;
long long mod(long long num){
    num -= num/m*m;
    if(num<0) num += m;
    return num;
}

string s;
int r, g, b, n, q;
int rp, rn, gp, gn;

long long solve(){
    long long result = 0LL;
    if((r+2*g)%3){
        result = pref12[b];
    }
    else{
        result = pref0[b];
    }

    if(n>1){
        if((n&1) && (!rp && !gn)){
            result--;
        }
        if((n&1) && (!rn && !gp)){
            result--;
        }
    }
    return mod(result);
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    pw2[0] = 1;
    pref0[0] = 0;
    pref12[0] = 1;
    for(int i=1; i<=200000; i++){
        pw2[i] = mod(pw2[i-1]*2);
        pref0[i] = mod(pw2[i] - pref0[i-1]);
        pref12[i] = mod(pw2[i] - pref12[i-1]);
    }

    cin >> n >> q;
    cin >> s;

    for(int i=0; i<n; i++){
        if(s[i]=='C'){
            r++;
            if(i&1) rn++;
            else rp++;
        }
        if(s[i]=='Z'){
            g++;
            if(i&1) gn++;
            else gp++;
        }
        if(s[i]=='N') b++;
    }

    int k; char kk;
    cout << solve() << '\n';
    
    for(int i=0; i<q; i++){
        cin >> k >> kk;
        k--;
        if(s[k] == 'C'){
            if(k&1) rn--;
            else rp--;
            r--;
        }
        
        if(s[k] == 'Z'){
            if(k&1) gn--;
            else gp--;
            g--;
        }
        if(s[k] == 'N') b--;

        s[k] = kk;

        if(kk == 'C'){
            if(k&1) rn++;
            else rp++;
            r++;
        }
        
        if(kk == 'Z'){
            if(k&1) gn++;
            else gp++;
            g++;
        }
        if(kk == 'N') b++;
        cout << solve() << '\n';
    }
}