Compilare: user.cpp: In function ‘int main()’: user.cpp:90:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < sol.size() - 1; i++) ^ user.cpp:77:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(inputFile.c_str(), "r", stdin); ^ user.cpp:78:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(outputFile.c_str(), "w", stdout); ^ user.cpp:80:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:83:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^