Compilare: main.cpp: In function 'int main()': main.cpp:2:166: warning: operation on 'j' may be undefined [-Wsequence-point] 2 | int64_t n,d[5002],m=666013,i=2,j,s;int main(){freopen("100m.in","r",stdin);freopen("100m.out","w",stdout);std::cin>>n;d[1]=1;for(;i<=n;i++)for(j=i;j;)d[j]=j*(d[j]+d[--j])%m;while(--i)s+=d[i];std::cout<<s%m;} | ^~~ main.cpp:2:166: warning: operation on 'j' may be undefined [-Wsequence-point] main.cpp:2:166: warning: operation on 'j' may be undefined [-Wsequence-point] main.cpp:2:166: warning: operation on 'j' may be undefined [-Wsequence-point] main.cpp:2:166: warning: operation on 'j' may be undefined [-Wsequence-point] main.cpp:2:166: warning: operation on 'j' may be undefined [-Wsequence-point]