/in/foo.cc: In function 'int main()':
/in/foo.cc:9:5: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     while(scanf("%d",&n),n)
     ^
/in/foo.cc:14:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d",&wall[j]);
                                 ^