Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:53:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < P.size(); i++) ^ user.cpp:54:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = i; j < P.size(); j++) { ^ user.cpp:67:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < P.size(); i++) ^ user.cpp:68:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = i; j < P.size(); j++) { ^ user.cpp: In function ‘int main()’: user.cpp:81:43: 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:82:45: 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:85:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ user.cpp:88:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^