/in/foo.cc: In function 'int main()':
/in/foo.cc:84:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < l; ++i) {
                     ^
/in/foo.cc:85:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int j = i; j<i+l; ++j)
                     ^