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

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

        //TODO uzyć lambdy

        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;
            }
        };

        return fun.apply(m, arr);
    }