foo.c: In function ‘judge_su’:
foo.c:18:5: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   18 |     if (num==1)
      |     ^~
foo.c:20:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
   20 |         for(i=2;i<num;i++)
      |         ^~~