Compilare: main.cpp: In function 'int main()': main.cpp:53:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arbore4.in","r",stdin); ^ main.cpp:54:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arbore4.out","w",stdout); ^ main.cpp:56:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:60:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^ main.cpp:65:30: warning: iteration 100005 invokes undefined behavior [-Waggressive-loop-optimizations] fact[i]=(1LL*fact[i-1]*i)%MOD; ~~~~~~~~^ main.cpp:64:18: note: within this loop for(int i=1;i<=2*NMAX;i++) ~^~~~~~~~