s=input()
t_c=0
r_c=0
e_c=0
for i in range(len(s)):
    if s[i]=='t':
        t_c+=1
    elif s[i]=='r':
        r_c+=1
    elif s[i]=='e':
        e_c+=1

print(min(t_c,r_c,e_c//2))