View Compilation Error

0_0_19802717_17879.cpp: In function 'void dfs(int, int)':
0_0_19802717_17879.cpp:18:29: error: 'strcmp' was not declared in this scope
   if(tmp==tar&&strcmp(ts,ans)>0)
                             ^
0_0_19802717_17879.cpp:19:17: error: 'strcpy' was not declared in this scope
    strcpy(ans,ts);
                 ^
0_0_19802717_17879.cpp: In function 'int main()':
0_0_19802717_17879.cpp:37:41: error: 'strcmp' was not declared in this scope
  while(cin>>tar>>s&&(tar||strcmp(s,"END")))
                                         ^
0_0_19802717_17879.cpp:39:31: error: 'memset' was not declared in this scope
   memset(vis,false,sizeof(vis));
                               ^
0_0_19802717_17879.cpp:42:17: error: 'strlen' was not declared in this scope
   dfs(0,strlen(s));
                 ^