{"trustable":true,"sections":[{"title":"","value":{"format":"HTML","content":"\u003cstyle type\u003d\"text/css\"\u003e .sampledata { font-family: \"Courier New\", Courier, monospace; white-space: pre; }\u003c/style\u003e\u003cp\u003e在2016年,佳媛姐姐刚刚学习了第二类斯特林数,非常开心。\u003c/p\u003e \n\u003cdiv\u003e\n 现在他想计算这样一个函数的值:\n\u003c/div\u003e \n\u003cdiv\u003e\n \u003cimg SRC\u003d\"CDN_BASE_URL/c1b4a9383336237755bb8c3746a885a1?v\u003d1591884099\" width\u003d\"437\" height\u003d\"47\" alt\u003d\"\"\u003e\n\u003c/div\u003e \n\u003cdiv\u003e\n S(i, j)表示第二类斯特林数,递推公式为:\n\u003c/div\u003e \n\u003cdiv\u003e\n S(i, j) \u003d j ∗ S(i − 1, j) + S(i − 1, j − 1), 1 \u0026lt;\u003d j \u0026lt;\u003d i − 1。\n\u003c/div\u003e \n\u003cdiv\u003e\n 边界条件为:S(i, i) \u003d 1(0 \u0026lt;\u003d i), S(i, 0) \u003d 0(1 \u0026lt;\u003d i)\n\u003c/div\u003e \n\u003cdiv\u003e\n 你能帮帮他吗?\n\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cp\u003e输入只有一个正整数\u003c/p\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cp\u003e\u0026nbsp;输出f(n)。由于结果会很大,输出f(n)对998244353(7 × 17 × 223 + 1)取模的结果即可。1 ≤ n ≤ 100000\u003c/p\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cspan class\u003dsampledata\u003e3\u003c/span\u003e\u003c/div\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cspan class\u003dsampledata\u003e87\u003c/span\u003e\u003c/div\u003e"}},{"title":"Hint","value":{"format":"HTML","content":"\u003cp\u003e\u003c/p\u003e"}}]}