Compilare: main.cpp: In function 'int main()': main.cpp:26:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1 ; i < ss.size() - 1 ; ++ i) { ~~^~~~~~~~~~~~~~~ main.cpp:17:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chei.in", "r", stdin) ; ^ main.cpp:18:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("chei.out", "w", stdout) ; ^