Compilare: user.cpp: In function ‘void solve_write()’: user.cpp:39:9: warning: unused variable ‘i’ [-Wunused-variable] int i, t, a, b; ^ user.cpp: In function ‘void read()’: user.cpp:10:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("citylog.in", "r", stdin); ^ user.cpp:11:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp: In function ‘void solve_write()’: user.cpp:42:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("citylog.out", "w", stdout); ^ user.cpp:45:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &t, &a, &b); ^ user.cpp: In function ‘void det_newb(int, int)’: user.cpp:20:33: warning: ‘z’ may be used uninitialized in this function [-Wmaybe-uninitialized] z = anc[anc[z][j - 1]][j - 1]; ^