Compilare: user.cpp: In function ‘int search(int)’: user.cpp:25:12: warning: unused variable ‘ans’ [-Wunused-variable] int i, ans = 0, y = x % mod, len = V[y].size(); ^ user.cpp: In function ‘void add(int)’: user.cpp:33:12: warning: unused variable ‘ans’ [-Wunused-variable] int i, ans = 0, y = x % mod, len = V[y].size(); ^ user.cpp: In function ‘void read()’: user.cpp:18:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("take5.in", "r", stdin); ^ user.cpp:19:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &s); ^ user.cpp:21:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^ user.cpp: In function ‘void write()’: user.cpp:62:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("take5.out", "w", stdout); ^