/in/foo.cc: In function 'void findp(int)':
/in/foo.cc:49:57: error: void value not ignored as it ought to be
 void findp(int x){return pre[x]==x?x:pre[x]=findp(pre[x]);}
                                                         ^
/in/foo.cc:49:57: error: return-statement with a value, in function returning 'void' [-fpermissive]
/in/foo.cc: In function 'int main()':
/in/foo.cc:64:38: error: 'a' was not declared in this scope
     c[++num].x=i,c[num].y=j,c[num].z=a[i];
                                      ^
/in/foo.cc:70:22: error: void value not ignored as it ought to be
   int f1=findp(c[i].x),f2=findp(c[i].y);
                      ^
/in/foo.cc:70:39: error: void value not ignored as it ought to be
   int f1=findp(c[i].x),f2=findp(c[i].y);
                                       ^