S=list(input())
t=0
r=0
e=0
for i in range(len(S)):
    if S[i]=="t":
        t+=1
    elif S[i]=="r":
        r+=1
    elif S[i]=="e":
        e+=1
t*=2
r*=2
m=t
if m>r:
    m=r
if m>e:
    m=e
e//=2
print (e)