/in/foo.cc: In function 'void link(int, int)':
/in/foo.cc:16:15: error: 'aa' was not declared in this scope
  lin[ai].from=aa;
               ^~
/in/foo.cc: In function 'void link0(int, int)':
/in/foo.cc:24:16: error: 'aa' was not declared in this scope
  lin0[ai].from=aa;
                ^~
/in/foo.cc: In function 'void tarjan(int, int)':
/in/foo.cc:41:32: error: 'mon' was not declared in this scope
    low[nod]=mon(low[nod],low[u]);
                                ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:62:17: error: 'ma' was not declared in this scope
   scanf("%d%d",&ma,&mb);
                 ^~
/in/foo.cc:62:21: error: 'mb' was not declared in this scope
   scanf("%d%d",&ma,&mb);
                     ^~
/in/foo.cc:61:7: warning: unused variable 'a' [-Wunused-variable]
   int a,b;
       ^
/in/foo.cc:61:9: warning: unused variable 'b' [-Wunused-variable]
   int a,b;
         ^
/in/foo.cc:69:3: error: 'a' was not declared in this scope
   a=belong[lin[i].from];
   ^
/in/foo.cc:70:3: error: 'b' was not declared in this scope
   b=belong[lin[i].to];
   ^
/in/foo.cc:77:11: error: 'a' was not declared in this scope
    sum++; a=i;
           ^
/in/foo.cc:83:18: error: 'a' was not declared in this scope
    if(belong[i]==a) printf("%d ",i);
                  ^