View Compilation Error

0_0_8599927_5677.cpp:7: error: expected constructor, destructor, or type conversion before '<' token
0_0_8599927_5677.cpp:7: error: expected `,' or `;' before '<' token
0_0_8599927_5677.cpp: In function `int dfs(int)':
0_0_8599927_5677.cpp:17: error: `tree' undeclared (first use this function)
0_0_8599927_5677.cpp:17: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_8599927_5677.cpp: In function `void DFS(int)':
0_0_8599927_5677.cpp:47: error: `tree' undeclared (first use this function)
0_0_8599927_5677.cpp:51: error: `max' undeclared (first use this function)
0_0_8599927_5677.cpp: In function `int main()':
0_0_8599927_5677.cpp:63: error: `tree' undeclared (first use this function)
0_0_8599927_5677.cpp:77: error: `max' undeclared (first use this function)