{"trustable":false,"prependHtml":"\u003cstyle type\u003d\"text/css\"\u003e\n #problem-body \u003e 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","sections":[{"title":"","value":{"format":"HTML","content":"Sakr is a new teacher in the university and he will give his first lecture on graphs.\n\u003cbr\u003e\u003cbr\u003e\nIn his first lecture, He drew an undirected graph on the board to explain some basic concepts of graphs on it.\n\u003cbr\u003e\u003cbr\u003e\nWhile he was explaining the basics he asked the students if anyone knows whether the graph is a tree or not.\n\u003cbr\u003e\u003cbr\u003e\nMariam, a clever student raised her hand to answer the question, Can you help her to answer correctly?"}},{"title":"Input","value":{"format":"HTML","content":"The first line of the input contains two integers $n,m$ $(0 \\le n \\le 10^4, 0 \\le m \\le 2.10^4)$ -- the number of nodes and edges of the graph respectively.\n\u003cbr\u003e\u003cbr\u003e\nThen $m$ lines follow:\n\u003cbr\u003e\u003cbr\u003e\nEach line contains two integers $u_i,v_i$ $(1 \\le u_i,v_i \\le n)$ -- There is an undirected edge between node $u_i$ and node $v_i$.\n\u003cbr\u003e\u003cbr\u003e\n\u003cb\u003eNote: there can be no nodes in the graph, also there can be no edges in the graph\u003c/b\u003e"}},{"title":"Output","value":{"format":"HTML","content":"Print \u0027YES\u0027 without quotes if the graph is a tree, otherwise print \u0027NO\u0027 without quotes.\n\u003cbr\u003e\u003cbr\u003e\n\u003cb\u003eA graph which contains $0$ nodes is considered a tree.\u003c/b\u003e"}},{"title":"Sample 1","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e\n5 4\n1 2\n2 3\n4 1\n5 2\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eYES\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}},{"title":"Sample 2","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e\n0 0\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eYES\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e"}},{"title":"Sample 3","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e\n5 5\n1 2\n2 3\n3 1\n5 2\n4 1\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eNO\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e"}},{"title":"Sample 4","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e\n5 3\n1 2\n2 3\n4 5\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eNO\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e"}}]}