Compilare: user.cpp: In function ‘int main()’: user.cpp:67:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v.size(); j++) { ~~^~~~~~~~~~ user.cpp:76:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v.size(); j++) { ~~^~~~~~~~~~ user.cpp:78:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s[r].size() == it.first) { ~~~~~~~~~~~~^~~~~~~~~~~ user.cpp:47:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unique.in", "r", stdin); ^ user.cpp:48:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unique.out", "w", stdout); ^ user.cpp:59:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a); ^