Compilare: main.cpp: In function 'int getMex(std::vector<int>&)': main.cpp:40:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i >= vals.size() || vals[i] != i) return i; ~~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:59:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pioni.in", "r", stdin); ^ main.cpp:60:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pioni.out", "w", stdout); ^