/in/foo.cc: In function 'int main()':
/in/foo.cc:22:15: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
     while(a[j]=0)
           ~~~~^~
/in/foo.cc:11:15: warning: 'n' is used uninitialized in this function [-Wuninitialized]
  for(int i=0;i<n;i++)
              ~^~
/in/foo.cc:6:11: warning: 'm' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int n,m;
           ^