s=input()
d={}
for i in s:
    if i=="t":
        if "t" not in d:
            d["t"]=1 
        else:
            d["t"]+=1 
    elif i=="r":
        if "r" not in d:
            d["r"]=1 
        else:
            d["r"]+=1
    elif i=="e":
        if "e" not in d:
            d["e"]=1 
        else:
            d["e"]+=1
a=0
if d["t"]>=1 and d["r"]>=1 and d["e"]>=2:
    a=min([d["t"],d["r"],d["e"]//2])
print(a)