Compilare: user.cpp: In function ‘int main()’: user.cpp:12:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("drum3.in", "r", stdin); ^ user.cpp:13:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("drum3.out", "w", stdout); ^ user.cpp:18:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &k); ^ user.cpp:40:18: warning: ‘p2’ may be used uninitialized in this function [-Wmaybe-uninitialized] ans = (1LL*p1*p2*2)%MOD; ^ user.cpp:40:18: warning: ‘p1’ may be used uninitialized in this function [-Wmaybe-uninitialized]