#include <bits/stdc++.h>

int main() {

  long Kr, Kb;
  char str[32];
  int size = 30;

  std::cin >> Kr >> Kb;
  scanf("%s", str);
  

  for(int i = 0; i < size; ++i) {
    if( str[i] == 'R' and  i+Kr < size ) {
      if( str[i+Kr] == 'R' ) {
	for(int j = i+Kr; j < size; ++j) {
	  str[j] = str[j+1];
	}
	i -= 1;
      }
    }
    else if( str[i] == 'B' and  i+Kb < size ) {
      if( str[i+Kb] == 'B' ) {
	for(int j = i+Kb; j < size; ++j) {
	  str[j] = str[j+1];
	}
	i -= 1;
      }
    }
  }

  
  std::cout << strlen(str) << std::endl;
  
  return 0;
}