/in/foo.c: In function 'main':
/in/foo.c:9:9: error: 'i' undeclared (first use in this function)
     for(i=0;i<n;i++)
         ^
/in/foo.c:9:9: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:7:20: warning: variable 'd' set but not used [-Wunused-but-set-variable]
     int weishu=0,n,d[N];
                    ^