def main():
    input_string = input()
    d = {"t":0, "r":0, "e":0}
    for e in list(input_string):
        if e == "t":
            d["t"] += 1
        elif e == "r":
            d["r"] += 1
        elif e == "e":
            d["e"] += 1

    l = []
    l.append(d["t"])
    l.append(d["r"])
    l.append(int(d["e"]/2))
    print(min(l))

if __name__ == '__main__':
    main()