/in/foo.cc: In function 'int main()':
/in/foo.cc:22:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=2;i<=p;i++)
                 ~^~~
/in/foo.cc:27:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1;i<=lef;i++)
                 ~^~~~~