#include <iostream>
using namespace std;

int main(){
	int h,s;
	string str;
	cin>>h>>s>>str;
	for(int i=0;i<str.size();i++){
		if(str[i]=='u'){
			if(s>0){
				s--;
			}
		}else{
			if(s<h){
				s++;
			}
		}
	}
	cout<<s;
}
/**************************************************************
	Problem: 1826
	User: admin
	Language: C++
	Result: Accepted
	Time:47 ms
	Memory:2076 kb
****************************************************************/