#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;
}
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