Compilare: user.cpp: In function ‘int main()’: user.cpp:7:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] {freopen("qmatrix.in","r",stdin); ^ user.cpp:8:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qmatrix.out","w",stdout); ^ user.cpp:9:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d",&n,&x,&y,&q); ^ user.cpp:20:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("\n%c %d %d",&aux,&l1,&c1); ^