Compilare: user.cpp: In function ‘bool chk(int)’: user.cpp:16:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < t.size(); i++) { ~~^~~~~~~~~~ user.cpp:17:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos[t[i] - 'a'].size() < cnt[p + 1][t[i] - 'a'] + r) { ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:26:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("balbaiala.in", "r", stdin); ^ user.cpp:27:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("balbaiala.out", "w", stdout); ^