Compilare: user.cpp: In function ‘void back(int, int, int)’: user.cpp:40:6: warning: unused variable ‘DX’ [-Wunused-variable] int DX,DY; ^ user.cpp:40:9: warning: unused variable ‘DY’ [-Wunused-variable] int DX,DY; ^ user.cpp: In function ‘int main()’: user.cpp:50:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("suma3.in","r",stdin); ^ user.cpp:51:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("suma3.out","w",stdout); ^ user.cpp:54:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&M); ^ user.cpp:60:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&a[i][j]); ^