n=list(map(int,input().split()))
h=n[0]
s=n[-1]
udzl=input()
for i in udzl:
    if i=="u":
        if s>0:
            s=s-1
    else:
        if s<h:
            s=s+1
print(s)
/**************************************************************
	Problem: 1826
	User: admin
	Language: Python
	Result: Accepted
	Time:603 ms
	Memory:34480 kb
****************************************************************/