#include <bits/stdc++.h>
#define PI 3.14159265358979323846
#define MAXINF (1e18L)
#define INF (1e9L)
#define EPS (1e-9)
#define MOD ((ll)(1e9+7))
#define REP(i, n) for(int i=0;i<int(n);++i)
#define REPA(x, v) for(auto&& x:v)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define RREP(i, n) for(int i=int(n)-1;i>=0;--i)
#define ALL(v) v.begin(),v.end()
#define FIND(v,x) (binary_search(ALL(v),(x)))
#define SORT(v) sort(ALL(v))
#define RSORT(v) sort(v.rbegin(),v.rend())
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl
#define Yes(n) cout<<((n)?"Yes":"No")<<endl
#define YES(n) cout<<((n)?"YES":"NO")<<endl
#define pb push_back
#define fi first
#define se second
using namespace std;
template<class A>void pr(A a){cout << (a) << endl;}
template<class A,class B>void pr(A a,B b){cout << a << " "  ;pr(b);}
template<class A,class B,class C>void pr(A a,B b,C c){cout << a << " " ;pr(b,c);}
template<class A,class B,class C,class D>void pr(A a,B b,C c,D d){cout << a << " " ;pr(b,c,d);}
template<class T> void pr_vec(vector<T> &v, char ep=' '){int n=v.size();REP(ni,n){cout<<v[ni];if(ni!=n-1)cout<<ep;}cout<<endl;};
template<class T> inline bool chmin(T& a, T b){return a>b ? a=b, true : false;}
template<class T> inline bool chmax(T& a, T b){return a<b ? a=b, true : false;}
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll,ll> pll;

int main(void)
{
    int N,X;
    cin >> N >> X;
    string S;
    cin >> S;
    REP(i, N){
        if(S[i] == 'o') X++;
        else X = max(0, X-1);
    }
    pr(X);
}
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <stack>
#include <cassert>
#include <map>
#include <numeric>
#include <cstring>
#include <set>
#include <ctime>
#include <queue>
#include <cmath>
#include <iomanip>
#include <iterator>
#include <bitset>
#include <unordered_set>

using namespace std;

clock_t timeStart, timeFinish;

void timeBegin() {
    timeStart = clock();
}

void timeEnd() {
    timeFinish = clock();
}

void timeDuration() {
    double time_taken = double(timeFinish - timeStart) / double(CLOCKS_PER_SEC);
    cout << "Time taken by program is : " << fixed << time_taken << setprecision(5);
    cout << " sec " << endl;
}

class InputReader {
public:
    InputReader() {
        input_file = stdin;
        cursor = 0;
        fread(buffer, SIZE, 1, input_file);
    }
    InputReader(const char *file_name) {
        input_file = fopen(file_name, "r");
        cursor = 0;
        fread(buffer, SIZE, 1, input_file);
    }
    inline InputReader &operator >>(int &n) {
        while((buffer[cursor] < '0' || buffer[cursor] > '9') && buffer[cursor] != '-') {
            advance();
        }
        int sign = 1;
        if (buffer[cursor] == '-') {
            sign = -1;
            advance();
        }
        n = 0;
        while('0' <= buffer[cursor] && buffer[cursor] <= '9') {
            n = n * 10 + buffer[cursor] - '0';
            advance();
        }
        n *= sign;
        return *this;
    }
    inline InputReader &operator >>(long long &n) {
        while((buffer[cursor] < '0' || buffer[cursor] > '9') && buffer[cursor] != '-') {
            advance();
        }
        int sign = 1;
        if (buffer[cursor] == '-') {
            sign = -1;
            advance();
        }
        n = 0;
        while('0' <= buffer[cursor] && buffer[cursor] <= '9') {
            n = n * 10 + buffer[cursor] - '0';
            advance();
        }
        n *= sign;
        return *this;
    }
private:
    FILE *input_file;
    static const int SIZE = 1 << 17;
    int cursor;
    char buffer[SIZE];
    inline void advance() {
        ++ cursor;
        if(cursor == SIZE) {
            cursor = 0;
            fread(buffer, SIZE, 1, input_file);
        }
    }
};

const int MAXN = 1000;
const int MOD = 1000000007;

int dp[1 + MAXN][2];

int main() {
    //timeBegin();
    //ifstream cin("input.txt");
    //ofstream cout("papagali.out");
    int n;
    char aa, ab, ba, bb;
    cin >> n >> aa >> ab >> ba >> bb;
    if (n <= 3) {
        cout << "1\n";
        return 0;
    }
    if ((ab == 'A' && aa == 'A') || (ab == 'B' && bb == 'B')) {
        cout << "1\n";
        return 0;
    }
    if ((ab == 'A' && aa == 'B' && ba == 'B') || (ab == 'B' && bb == 'A' && ba == 'A')) {
        int answer = 1;
        for (int i = 1; i <= n - 3; i++) {
            answer *= 2;
            if (answer >= MOD) {
                answer -= MOD;
            }
        }
        cout << answer << "\n";
        return 0;
    }
    dp[1][0] = dp[1][1] = 1;
    for (int i = 2; i <= n - 3; i++) {
        dp[i][0] = dp[i - 1][0] + dp[i - 1][1];
        if (dp[i][0] >= MOD) {
            dp[i][0] -= MOD;
        }
        dp[i][1] = dp[i - 1][0];
    }
    int answer = dp[n - 3][0] + dp[n - 3][1];
    if (answer >= MOD) {
        answer -= MOD;
    }
    cout << answer << "\n";
    return 0;
}
