/in/foo.c: In function 'main':
/in/foo.c:9:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);    //输入数据个数
     ^
/in/foo.c:12:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &a[i]);
         ^