Compilare: user.cpp: In function ‘bool solve(int)’: user.cpp:105:21: warning: unused variable ‘x’ [-Wunused-variable] int x = ++ P[j]; ^ user.cpp:90:15: warning: unused variable ‘x’ [-Wunused-variable] int i, j, x, k = 0; ^ user.cpp: In function ‘void print_sol()’: user.cpp:125:25: warning: unused variable ‘p’ [-Wunused-variable] int i, j, x, k = 0, p = 0; ^ user.cpp: In function ‘void read()’: user.cpp:46:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("danger.in", "r", stdin); ^ user.cpp:47:29: 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:53:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &V[i][j]); ^ user.cpp: In function ‘void write()’: user.cpp:156:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("danger.out", "w", stdout); ^