Compilare: main.cpp: In function 'int main()': main.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0, j = 0; i < lst.size(); i = j) { ~~^~~~~~~~~~~~ main.cpp:25:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < lst.size() and lst[i].first == lst[j].first) ~~^~~~~~~~~~~~ main.cpp:17:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("teste.in", "r", stdin); ^ main.cpp:18:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("teste.out", "w", stdout); ^