if __name__ == '__main__':
    S = input(">>")
    num = 0
    t = 0
    r = 0
    e = 0
    for str1 in S:
        if(str1 == "t"):
            t += 1
        elif(str1 == "r"):
            r += 1
        elif(str1 == "e"):
            e += 1
    e /= 2
    e = int(e)
    while(e != 0):
        if(t > 0):
            t -= 1
        if(r > 0):
            r -= 1
        if(e > 0):
            e -= 1
            num += 1;
    print(num)