Compilare: user.cpp: In function ‘int main()’: user.cpp:13:34: warning: suggest parentheses around ‘-’ in operand of ‘&’ [-Wparentheses] a[i & 1][i] = (long long)a[1 - i & 1][i - 1] * i % MOD; ^ user.cpp:15:41: warning: suggest parentheses around ‘-’ in operand of ‘&’ [-Wparentheses] a[i & 1][k] = (long long)k * (a[1 - i & 1][k] + a[1 - i & 1][k - 1]) % MOD; ^ user.cpp:15:59: warning: suggest parentheses around ‘-’ in operand of ‘&’ [-Wparentheses] a[i & 1][k] = (long long)k * (a[1 - i & 1][k] + a[1 - i & 1][k - 1]) % MOD; ^ user.cpp:6:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("100m.in", "r", stdin); ^ user.cpp:7:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("100m.out", "w", stdout); ^ user.cpp:9:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^