static Long fibonacci(int m){
        if(m < 0) {
            throw new IllegalArgumentException("index must be >= 0");
        }

        Long[] arr = new Long[m+1];

        //TODO uzyć lambdy
        return fun.apply(m, arr);
    }

    static BiFunction<Integer, Long[], Long> fun = (n, memo) ->{
        if(memo[n] != null){
            return memo[n];
        } else {
            Long val;
            if(n > 1){
                val = Main.fun.apply(n-1, memo) + Main.fun.apply(n-2, memo);
            }
            else {
                val = 1L;
            }
            memo[n] = val;
            return val;
        }
    };