#include <iostream>
#include <vector>
using namespace std;
vector <int> v;
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, k;
    cin >> n >> k;
    v.resize(n);
    for(int i = 0; i < n; i++)
    {v[i]=i+1;}
    string a;
    cin >> a;
    for(int i = 0; i < k; i++)
    {
     if(a[i] == 'A')
     {
      int b = v[0];
      v.erase(v.begin());
      v.push_back(b);
     }
     if(a[i] == 'B')
     {
      int b = v[1];
      v.erase(v.begin() + 1);
      v.push_back(b);
     }
    }
    cout << v[0];
    return 0;
}