Compilare: user.cpp: In function ‘int main()’: user.cpp:58:54: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(u - p +1 < su - sp +1 && st.size() == N) ^ user.cpp:67:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(u - p +1 < su - sp +1 && st.size() == N) sp = p, su = u; ^ user.cpp:68:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(st.size() == N) ^ user.cpp:16:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(F, "%d ", &n); ^ user.cpp:19:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(F, "%d ", &v[i]); ^