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#include <bits/stdc++.h>
using namespace std;

long long MOD = 1000000007;

int c=0,z=0,cp=0,cn=0,zp=0,zn=0;
int n, q;
short type[3];
long long fact[200001];
long long sum[200001][3];
string str;




long long gcdExtended(long long a, long long b, long long *x, long long *y) {
    if (a == 0) {
        *x = 0, *y = 1;
        return b;
    }
    long long x1, y1;
    long long gcd = gcdExtended(b%a, a, &x1, &y1);
    *x = y1 - (b/a) * x1;
    *y = x1;
    return gcd;
}

long long modInverse(long long b, long long m) {
    long long x, y;
    long long g = gcdExtended(b, m, &x, &y);
    if (g != 1) return -1;
    return (x%m + m) % m;
}

long long modDivide(long long a, long long b) {
    a = a % MOD;
    long long inv = modInverse(b, MOD);
    if (inv != -1) {
        return (inv * a) % MOD;
    }
    cout << "ERROR";
    return 0;
}

long long choose(long long n, long long k) {
    return modDivide(modDivide(fact[n], fact[k]), fact[n-k]);
}




//0-C, 1-Z, 2-CZ/ZC
int checkType(int c, int z) {
    while(c>1 || z>1) {
        if(c>1) {
            z += c/2;
            c %= 2;
        }
        if(z>1) {
            c += z/2;
            z %= 2;
        }
    }
    if(c==1) {
        if(z==1) {
            return 2;
        } else {
            return 0;
        }
    } else {
        return 1;
    }
}

bool correct(int c) {
    return type[c%3] <= 1;
}

long long dec(long long ret) {
    if(n>1 && correct(n/2)) {
        if(cp==0 && zn==0) ret--;
        if(cn==0 && zp==0) ret--;
        if(ret < 0) ret += MOD;
    }
    return ret;
}

int main() {
    cin >> n >> q >> str;
    for(int i=0;i<n;i++) {
        char ch = str[i];
        if(ch == 'C') {
            c++;
            if(i%2==0) {
                cp++;
            } else {
                cn++;
            }
        } else if(ch == 'Z') {
            z++;
            if(i%2==0) {
                zp++;
            } else {
                zn++;
            }
        }
    }
    for(int i=0;i<=min(n,2);i++) {
        type[i] = checkType(i, n-i);
    }
    fact[0] = 1;
    for(int i=1;i<=n;i++) {
        fact[i] = (fact[i-1] * i) % MOD;
    }
    sum[0][0]=1;
    sum[0][1]=0;
    sum[0][2]=0;
    for(int i=1;i<=n;i++) {
        for(int j=0;j<=2;j++) {
            for(int k=0;k<=2;k++) {
                if(k == j || k == j-1 || k == j+2) {
                    sum[i][j] += sum[i-1][k];
                }
            }
            /*if(j==0) {
                sum[i][j]++;
            }
            if(j==(i-1)%3) {
                sum[i][j]++;
            }*/
            sum[i][j]%=MOD;
        }
        //cout << i << ". " << sum[i][0] <<"+"<< sum[i][1] <<"+"<< sum[i][2]<<"="<<(sum[i][0] + sum[i][1] + sum[i][2]) << "\n";
    }

    long long ret = 0;
    int N = n-c-z;
    for(int i=0;i<=2;i++) {
        if(correct(c+i)) {
            ret = (ret + sum[N][i]) % MOD;
        }
    }
    /*for(int i=0;i<=N;i++) {
        if(correct(c + i)) {
            ret = (ret + choose(N, i)) % MOD;
            cout << i << ": " << choose(N, i) << "\n";
        }
    }*/
    cout << dec(ret) << "\n";
    int pos;
    char ch;
    for(int qq=0;qq<q;qq++) {
        int deltaC=0, deltaZ=0;
        cin >> pos >> ch;
        pos--;
        if(str[pos] == 'C') {
            deltaC--;
        } else if(str[pos] == 'Z') {
            deltaZ--;
        }
        str[pos] = ch;
        if(str[pos] == 'C') {
            deltaC++;
        } else if(str[pos] == 'Z') {
            deltaZ++;
        }
        c += deltaC;
        z += deltaZ;
        if(pos%2==0) {
            cp += deltaC;
            zp += deltaZ;
        } else {
            cn += deltaC;
            zn += deltaZ;
        }
        N = n-c-z;
        ret = 0;
        for(int i=0;i<=2;i++) {
            if(correct(c+i)) {
                ret = (ret + sum[N][i]) % MOD;
            }
        }
        cout << dec(ret) << "\n";
    }
    return 0;
}