Compilare: user.cpp: In function ‘int main()’: user.cpp:17:22: warning: left operand of comma operator has no effect [-Wunused-value] for(m=1;m+i-1<=n,m+j-1<=n;m+=250) ^ user.cpp:20:22: warning: left operand of comma operator has no effect [-Wunused-value] for(m=x;m+i-1<=n,m+j-1<=n;m++) ^ user.cpp:5:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("custi.in","r",stdin); ^ user.cpp:6:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("custi.out","w",stdout); ^ user.cpp:7:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:10:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&a[i][j]); ^