Compilare: main.cpp: In function 'long long int solve(int, int)': main.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A.size(); ++i) { ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:57:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.in", "r", stdin); ^ main.cpp:58:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.out", "w", stdout); ^