Compilare: user.cpp: In function ‘int match(int)’: user.cpp:15:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<v[k].size(); ++i) ^ user.cpp:22:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<v[k].size(); ++i) ^ user.cpp: In function ‘void f(int)’: user.cpp:32:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[k].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:43:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("felinar.in", "r", stdin); ^ user.cpp:44:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("felinar.out", "w", stdout); ^ user.cpp:45:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &m); ^ user.cpp:48:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &x, &y); ^