Compilare: main.cpp:2:330: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] 2 | using namespace std;const int N=(1<<16);void DFT(vector<complex<double>>&a,bool rev){int n=a.size(),i,step,j;auto b=a;for(step=n/2;step;step/=2){for(i=0;i<n/2;i+=step){auto wn=polar(1.0,2.0*M_PI*(rev?-i:i)/n);for(j=0;j<step;++j){auto u=a[i*2+j],v=wn*a[i*2+j+step];b[i+j]=u+v;b[i+n/2+j]=u-v;}}swap(a,b);}if(rev)for(auto&x:a)x/=n;}main(){ifstream g("bacterii2.in");ofstream l("bacterii2.out");int t,n,x,i,cnt,m; g>>t;while(t--){vector<complex<double>>p(N),q(N);g>>n;while(n--){;g>>x;p[x]+=1;}g>>m;while(m--){;g>>x;q[x]+=1;}DFT(p,0);DFT(q,0);for(i=0;i<N;++i)p[i]*=q[i];DFT(p,1);for(i=0;i<N;++i){cnt=round(real(p[i]));if(cnt>0)l<<i<<" "<<cnt<<'\n';}l<<'\n';}} | ^~~~