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#include <bits/stdc++.h>
#define mod 1000000007
#define inv3 333333336

using namespace std;

typedef long long ll;

char seq[200010];
int pow2[200010];
int a[6]={2, 1, -1, -2, -1, 1};
int colours[3];
int sth[2][2];

int f(int n, int k)
{
    return (((ll)pow2[n]+a[(6+(n-2*k)%6)%6])*inv3)%mod;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    int n,q;
    cin>>n>>q;
    pow2[0]=1;
    for(int i=1; i<=n; i++)
        pow2[i]=(2*pow2[i-1])%mod;
    for(int i=0; i<n; i++)
    {
        cin>>seq[i];
        if(seq[i]=='C')
        {
            sth[i%2][0]++;
            colours[0]++;
        }
        else if(seq[i]=='Z')
        {
            sth[i%2][1]++;
            colours[1]++;
        }
        else
        {
            colours[2]++;
        }
    }

    int res=(mod+(pow2[colours[2]]-f(colours[2],((colours[2]-(colours[1]-colours[0]))*2)%3))%mod)%mod;
    // cout<<res<<" "<<pow2[colours[2]]<<" "<<((colours[2]-(colours[1]-colours[0]))*2)%3<<"\n";
    if(n==1)
        cout<<res;
    else if(colours[2]==n)
    {
        if(n%2==0)
            cout<<res;
        else
            cout<<res-2;
    }

    else if((sth[0][0]==0&&sth[1][1]==0)||(sth[1][0]==0&&sth[0][1]==0))
    {
        if(n%2==0)
            cout<<res;
        else
            cout<<res-1;
    }
    else
        cout<<res;
    cout<<"\n";

    for(int i=0; i<q; i++)
    {
        int p;
        char c;
        cin>>p>>c;
        p-=1;
        if(seq[p]=='C')
        {
            sth[p%2][0]--;
            colours[0]--;
        }
        else if(seq[p]=='Z')
        {
            sth[p%2][1]--;
            colours[1]--;
        }
        else
        {
            colours[2]--;
        }


        if(c=='C')
        {
            sth[p%2][0]++;
            colours[0]++;
        }
        else if(c=='Z')
        {
            sth[p%2][1]++;
            colours[1]++;
        }
        else
        {
            colours[2]++;
        }

        seq[p]=c;


        int res=(mod+(pow2[colours[2]]-f(colours[2],((colours[2]-(colours[1]-colours[0]))*2)%3))%mod)%mod;
        if(n==1)
            cout<<res;
        else if(colours[2]==n)
        {
            if(n%2==0)
                cout<<res;
            else
                cout<<res-2;
        }
        else if((sth[0][0]==0&&sth[1][1]==0)||(sth[1][0]==0&&sth[0][1]==0))
        {
            if(n%2==0)
                cout<<res;
            else
                cout<<res-1;
        }
        else
            cout<<res;
        cout<<"\n";
    }
}