Compilare: main.cpp: In function 'int main()': main.cpp:20:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1 ; i <= ss.size() - 2 ; ++ i) { ~~^~~~~~~~~~~~~~~~ main.cpp:19:13: warning: unused variable 'ener' [-Wunused-variable] int ener, i, j, k ; ^~~~ main.cpp:9:40: 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:10:42: 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) ; ^