Compilare: user.cpp: In function ‘int main()’: user.cpp:19:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ture.out", "w", stdout); ^ user.cpp:23:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &N, &M, &K, &P); ^ user.cpp:29:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] !swap ? blocked[x][y] = 1 : blocked[y][x] = 1; ^