{"trustable":false,"prependHtml":"\u003cscript\u003e window.katexOptions \u003d { disable: true }; \u003c/script\u003e\n\u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {\n inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027], [\u0027$\u0027,\u0027$\u0027]],\n displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027], [\u0027$$\u0027,\u0027$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\" type\u003d\"text/javascript\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"\u003cscript type\u003d\u0027text/x-mathjax-config\u0027\u003eMathJax.Hub.Config({tex2jax: { inlineMath: [[\u0027$\u0027,\u0027$\u0027]] } }); \u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027 src\u003d\u0027https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\u0027\u003e\u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027\u003esetTimeout(function(){MathJax.Hub.Queue([\u0027Typeset\u0027, MathJax.Hub, \u0027left_view\u0027]);}, 2000);\u003c/script\u003e\n\u003cdiv class\u003d\"panel_content\"\u003e\n tgy是一名可怜的太刀侠,正要去狩猎青电主,没想到狡猾的青电主竟然躲到了新大陆的某个区里。由于新大陆的道路上充满台阶,猎人们举步维艰,tgy需要你为他选择一条从营地到青电主所在位置,跨越台阶数最少的路径\n \u003cbr\u003e \n \u003cbr\u003e \n\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"输入包括多组数据。每组数据第一行是两个整数N、M(N\u0026lt;\u003d100,M\u0026lt;\u003d10000),N表示新大陆有多少个区,标号为1的区是营地所在地,标号为N的区是青电主所在地,M则表示在新大陆有几条路。N\u003dM\u003d0表示输入结束。接下来M行,每行包括3个整数A,B,C(1\u0026lt;\u003dA,B\u0026lt;\u003dN,1\u0026lt;\u003dC\u0026lt;\u003d1000),表示在A区与B区之间有一条双向道路,路上有C个台阶。 \n\u003cbr\u003e输入保证至少存在1条从营地到青电主的路线。 \n\u003cbr\u003e"}},{"title":"Output","value":{"format":"HTML","content":"对于每组输入,输出一行,表示从营地到青电主最少需要跨越的台阶数"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cpre\u003e2 1\n1 2 3\n3 3\n1 2 5\n2 3 5\n3 1 2\n0 0\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cpre\u003e3\n2\u003c/pre\u003e"}}]}