Compilare: user.cpp: In function ‘void solve()’: user.cpp:44:15: warning: unused variable ‘k’ [-Wunused-variable] int i, j, k; ^ user.cpp: In function ‘void read()’: user.cpp:13:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rama.in", "r", stdin); ^ user.cpp:14:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &N, &M); ^ user.cpp:17:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s\n", a[i] + 1); ^ user.cpp: In function ‘void write()’: user.cpp:125:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rama.out", "w", stdout); ^