n=int(input()) a=input() s=0 k=1 if a[0]=='V': s+=1 elif a[0]=='X': s-=1 for i in range(1,n): if a[i]=='V': s+=1 if a[i]==a[i-1]: k+=1 else: if k>=3: s+=k-2 k=1 if i==n-1 and k>=3: s+=k-2 elif a[i]=='X': s-=1 print(s)