Compilare: user.cpp: In function ‘int main()’: user.cpp:48:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() != k) { ^ user.cpp:25:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d %d", &k, &n); ^ user.cpp:31:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &x); ^