from collections import Counter

N=int(input())
S=input().strip()

C=Counter(S)
ANS=0

ALL="abcdefghijklmnopqrstuvwxyz"
YUKI="yuki"

for i in range(10**6):
    #print(C)

    if C["y"]>0 and C["u"]>0 and C["k"]>0 and C["i"]>0:
        C["y"]-=1
        C["u"]-=1
        C["k"]-=1
        C["i"]-=1
        
        for s in ALL:
            if C[s]>0:
                C[s]-=1
                ANS+=1
                break

        continue

    if C["y"]>0 and C["u"]>0 and C["k"]>0:
        C["y"]-=1
        C["u"]-=1
        C["k"]-=1
        
        for s in ALL:
            if s>"i" and C[s]>0:
                C[s]-=1
                ANS+=1
                break

        continue

    if C["y"]>0 and C["u"]>0:
        C["y"]-=1
        C["u"]-=1
        
        for s in ALL:
            if s>"k" and C[s]>0:
                C[s]-=1
                ANS+=1
                break
        continue

    if C["y"]>0:
        C["y"]-=1
        
        for s in ALL:
            if s>"u" and C[s]>0:
                C[s]-=1
                ANS+=1
                break

        continue

    if C["z"]>0:
        C["z"]-=1
        ANS+=1
    else:
        break

    

print(ANS)