Compilare: user.cpp: In function ‘void solve()’: user.cpp:87:9: warning: unused variable ‘i’ [-Wunused-variable] int i, j; ^ user.cpp:87:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j; ^ user.cpp: In function ‘void read()’: user.cpp:35:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("vis.in", "r", stdin); ^ user.cpp:36:72: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %lld %lld %d %d %d %d", &n, &k1, &k2, &l1, &c1, &l2, &c2); ^ user.cpp:39:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i][j]); ^ user.cpp: In function ‘void write()’: user.cpp:104:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("vis.out", "w", stdout); ^