{"trustable":false,"prependHtml":"\u003cstyle type\u003d\"text/css\"\u003e\n section pre {\n display: block;\n padding: 9.5px;\n margin: 0 0 10px;\n font-size: 13px;\n line-height: 1.42857143;\n word-break: break-all;\n word-wrap: break-word;\n color: #333;\n background: rgba(255, 255, 255, 0.5);\n border: 1px solid #ccc;\n border-radius: 6px;\n }\n\u003c/style\u003e\n\u003cscript\u003e\n window.katexOptions \u003d {\n delimiters: [\n {left: \u0027\\\\(\u0027, right: \u0027\\\\)\u0027, display: false},\n {left: \u0027\\\\[\u0027, right: \u0027\\\\]\u0027, display: true}\n ]\n };\n\u003c/script\u003e\n","sections":[{"title":"Problem Statement","value":{"format":"PLAIN","content":"Có cầu thang N bậc. Bạn đang ở bậc thứ 0.\n\nBạn có thể leo một hoặc 2 bậc cùng lúc. Tuy nhiên cầu thang có các vị trí a_1 ... a_m là không được đi vào.\n\nIn ra số cách để leo lên bậc thứ N trong mod 10^9 + 7."}},{"title":"Constraints","value":{"format":"PLAIN","content":"1 \u003c\u003d N \u003c\u003d 100000\n0 \u003c\u003d M \u003c\u003d N - 1"}},{"title":"Input","value":{"format":"PLAIN","content":"N M\na_1\n...\na_M"}},{"title":"Sample Input 1","value":{"format":"PLAIN","content":"6 1\n3\n"}},{"title":"Sample Output 1","value":{"format":"PLAIN","content":"4"}},{"title":"Sample Input 2","value":{"format":"PLAIN","content":"10 2\n4\n5\n"}},{"title":"Sample Output 2","value":{"format":"PLAIN","content":"0\n"}},{"title":"Sample Input 3","value":{"format":"PLAIN","content":"100 5\n1\n23\n45\n67\n89\n\u003c/pre\u003e"}},{"title":"Sample Output 3","value":{"format":"PLAIN","content":"608200469"}}]}