/in/foo.c:5:5: error: variably modified 'max1' at file scope
 int max1[maxn];
     ^~~~
/in/foo.c:6:5: error: variably modified 'visit' at file scope
 int visit[maxn];
     ^~~~~
/in/foo.c:7:5: error: variably modified 'q' at file scope
 int q[maxn];
     ^
/in/foo.c:10:5: error: variably modified 'in' at file scope
 int in[maxn]={0};
     ^~
/in/foo.c:29:4: error: variably modified 'G' at file scope
  g G[maxn];
    ^
/in/foo.c:34:5: error: variably modified 'color' at file scope
 int color[maxn][maxn]={{0}};
     ^~~~~
/in/foo.c:34:5: error: variably modified 'color' at file scope
/in/foo.c: In function 'init':
/in/foo.c:73:11: warning: unused variable 'q' [-Wunused-variable]
   pnode p,q;
           ^
/in/foo.c:73:9: warning: unused variable 'p' [-Wunused-variable]
   pnode p,q;
         ^
/in/foo.c: In function 'work':
/in/foo.c:135:15: error: 'true' undeclared (first use in this function)
  visit[begin]=true;
               ^~~~
/in/foo.c:135:15: note: each undeclared identifier is reported only once for each function it appears in