View Compilation Error

0_0_26125042_5385.cpp: In function 'void dfs(int, int, int)':
0_0_26125042_5385.cpp:18:31: error: 'printf' was not declared in this scope
     printf("%d %d %d\n",fa,u,c);
                               ^
0_0_26125042_5385.cpp: In function 'int main()':
0_0_26125042_5385.cpp:40:25: error: 'stdin' was not declared in this scope
     freopen("i.txt","r",stdin);
                         ^
0_0_26125042_5385.cpp:40:30: error: 'freopen' was not declared in this scope
     freopen("i.txt","r",stdin);
                              ^
0_0_26125042_5385.cpp:41:18: error: 'scanf' was not declared in this scope
     scanf("%d",&T);
                  ^
0_0_26125042_5385.cpp:45:35: error: 'memset' was not declared in this scope
         memset(head,-1,sizeof head);
                                   ^
0_0_26125042_5385.cpp:63:37: error: 'printf' was not declared in this scope
         printf("%d %d\n",maxn1,maxn2);
                                     ^