Compilare: user.cpp: In function ‘int main()’: user.cpp:10:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ec.in","r",stdin); ^ user.cpp:11:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ec.out","w",stdout); ^ user.cpp:12:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&n,&k); ^ user.cpp:13:67: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1; i<=n; i++) for (j=1; j<=n; j++) scanf("%d",&a[i][j]); ^ user.cpp:14:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("\n"); ^ user.cpp:17:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); ^ /tmp/ccwyyvMF.o: In function `main': user.cpp:(.text.startup+0x118): warning: the `gets' function is dangerous and should not be used.