/in/foo.cc:3:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:5:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<=n;i++)scanf("%u",&num[i]);
              ~^~~
/in/foo.cc:6:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<=n;i++)for(int j=1;i*j<=n;j++)t[i*j]+=num[i];
              ~^~~
/in/foo.cc:6:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<=n;i++)for(int j=1;i*j<=n;j++)t[i*j]+=num[i];
                                   ~~~^~~
/in/foo.cc:7:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<=n;i++)ans^=t[i];
              ~^~~