Compilare: user.cpp: In function ‘int main()’: user.cpp:2:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("tije.in","r",stdin);freopen("tije.out","w",stdout);int N,i,j,k;scanf("%d", &N);for(i=N-1;i>=1;i--){for(j=N;j>=1;j--) for(k=1;k<=i;k++) printf("%d %d\n", j, j+1);for(j=1;j<=i;j++) printf("%d %d\n", N+1, 1);}return 0;} ^ user.cpp:2:71: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("tije.in","r",stdin);freopen("tije.out","w",stdout);int N,i,j,k;scanf("%d", &N);for(i=N-1;i>=1;i--){for(j=N;j>=1;j--) for(k=1;k<=i;k++) printf("%d %d\n", j, j+1);for(j=1;j<=i;j++) printf("%d %d\n", N+1, 1);}return 0;} ^ user.cpp:2:99: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("tije.in","r",stdin);freopen("tije.out","w",stdout);int N,i,j,k;scanf("%d", &N);for(i=N-1;i>=1;i--){for(j=N;j>=1;j--) for(k=1;k<=i;k++) printf("%d %d\n", j, j+1);for(j=1;j<=i;j++) printf("%d %d\n", N+1, 1);}return 0;} ^