Compilare: user.cpp: In function ‘int main()’: user.cpp:32:27: warning: operation on ‘a[0][j]’ may be undefined [-Wsequence-point] a[0][j]=a[0][j]=-1; ^ user.cpp:33:31: warning: operation on ‘a[(n + 1)][j]’ may be undefined [-Wsequence-point] a[n+1][j]=a[n+1][j]=-1; ^ user.cpp:13:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("insule.in","r",stdin); ^ user.cpp:14:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:19:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%1d",&num); ^ user.cpp:23:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("\n"); ^