Accepted
/in/foo.cc: In function 'int main()':
/in/foo.cc:21:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i=0;i<len;i++) n=n*k+ch(nn[i]);
~^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:21:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i=0;i<len;i++) n=n*k+ch(nn[i]);
~^~~~
