/in/foo.cc: In function 'int main()':
/in/foo.cc:40:1: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
 for(int i=1;i<k;i++)//i和j都必须要小于k以此保证此环中结论成立 
 ^~~
/in/foo.cc:44:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
   for(int i=1;i<=N;i++)
   ^~~
/in/foo.cc:31:10: warning: unused variable 'temp' [-Wunused-variable]
  int dis,temp;
          ^~~~