Compilare: user.cpp: In function ‘void read()’: user.cpp:22:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&n,&m,&K); ^ user.cpp:26:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] {scanf("%d",&a[i][j]);printf("%d ",a[i][j]);} ^ user.cpp: In function ‘int main()’: user.cpp:141:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unlock.in","r",stdin); ^ user.cpp:142:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unlock.out","w",stdout); ^ user.cpp:144:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&T); ^ user.cpp: In function ‘void clear_data()’: user.cpp:135:19: warning: iteration 254u invokes undefined behavior [-Waggressive-loop-optimizations] a[i][j]=0; ^ user.cpp:133:5: note: containing loop for(int i=1;i<=1000;i++) ^ user.cpp:135:19: warning: iteration 254u invokes undefined behavior [-Waggressive-loop-optimizations] a[i][j]=0; ^ user.cpp:134:9: note: containing loop for(int j=1;j<=1000;j++) ^