A. Company Merging

int main(){
    // input
    ll N; 
    cin>>N;

    VV A(N);
    rep(i,N){
      ll n;cin>>n;
      rep(j,n){
        ll a;cin>>a;
        A[i].push_back(a);
      }
    }

    ll ma = 0;
    rep(i,N){
      chmax(ma, MAX(A[i]));
    }

    ll sum=0;
    rep(i,N){
      sum += (ma-MAX(A[i])) * SZ(A[i]);
    }
    p(sum);
    
    return 0;
}