class Problem0279:
    def solve(this):
        res = {}
        for c in list(input()):
            res[c] = res.get(c, 0) + 1
        cnt = min(res.get('t', 0), res.get('r', 0), res.get('e', 0) // 2)
        print(cnt)

if __name__ == "__main__":
    problem = Problem0279()
    problem.solve()