Compilare: user.cpp: In function ‘void solve()’: user.cpp:63:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j; ^ user.cpp: In function ‘void read()’: user.cpp:26:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("checkin.in", "r", stdin); ^ user.cpp:27:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("checkin.out", "w", stdout); ^ user.cpp:28:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ user.cpp:30:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &v[i].a, &v[i].b); ^ user.cpp:31:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &K, &P); ^