Compilare: main.cpp: In function 'int main()': main.cpp:11:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < s.size() ; ++ i) { ~~^~~~~~~~~~ main.cpp:15:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < s.size() ; ++ i) { ~~^~~~~~~~~~ main.cpp:18:72: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ((mp[j] > 0 && j != Previous && Good == true) || (mp[j] >= (s.size() - i) / 2 + 1 && j != Previous)) { main.cpp:5:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ordine.in", "r", stdin) ; ^ main.cpp:6:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ordine.out", "w", stdout) ; ^