Compilare: user.cpp: In function ‘int main()’: user.cpp:3:75: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int a[2][5005];int main(){freopen("100m.in","r",stdin);freopen("100m.out","w",stdout);int n;scanf("%d", &n);a[1][1] = 1;for(int i=2;i<=n;++i){int p=i&1;a[p][1]=1;a[p][i]=(long long)a[1-p][i-1]*i%MOD;for(int k=2;k<i;++k){a[p][k]=(long long)k*(a[1-p][k]+a[1-p][k-1])%MOD;}}int s=0;for(int i=1;i<=n;++i){s=(s+a[n&1][i])%MOD;}printf("%d\n",s);return 0;} ^ user.cpp:3:106: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int a[2][5005];int main(){freopen("100m.in","r",stdin);freopen("100m.out","w",stdout);int n;scanf("%d", &n);a[1][1] = 1;for(int i=2;i<=n;++i){int p=i&1;a[p][1]=1;a[p][i]=(long long)a[1-p][i-1]*i%MOD;for(int k=2;k<i;++k){a[p][k]=(long long)k*(a[1-p][k]+a[1-p][k-1])%MOD;}}int s=0;for(int i=1;i<=n;++i){s=(s+a[n&1][i])%MOD;}printf("%d\n",s);return 0;} ^ user.cpp:3:128: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int a[2][5005];int main(){freopen("100m.in","r",stdin);freopen("100m.out","w",stdout);int n;scanf("%d", &n);a[1][1] = 1;for(int i=2;i<=n;++i){int p=i&1;a[p][1]=1;a[p][i]=(long long)a[1-p][i-1]*i%MOD;for(int k=2;k<i;++k){a[p][k]=(long long)k*(a[1-p][k]+a[1-p][k-1])%MOD;}}int s=0;for(int i=1;i<=n;++i){s=(s+a[n&1][i])%MOD;}printf("%d\n",s);return 0;} ^