Compilare: user.cpp: In function ‘int main()’: user.cpp:16:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; k < s2.size(); i++) { ^ user.cpp:7:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sr.in", "r", stdin); ^ user.cpp:8:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sr.out", "w", stdout); ^