S=list(input())
t=S.count("t")
r=S.count("r")
e=S.count("e")
e=e//2
if (t>=r) :
    if (r>=e) :
        print(e)
    else:
        print(r)
elif (r>t) :
    if (t>e) :
        print(e)
    else:
        print(t)
elif (r>=e) :
    if (e>=t) :
        print(t)
    else:
        print(e)
elif (e>r) :
    if (r>t) :
        print(t)
    else:
        print(r)
elif (t>=e) :
    if (e>=r) :
        print(r)
    else:
        print(e)
elif (e>t) :
    if (t>r) :
        print(r)
    else:
        print(t)
else:
    pass