Solution
= Solution
To first order the conditions are $\partial_{p_j}δq_i-\partial_{p_i}δq_j=0$, $\partial_{q_j}δp_i-\partial_{q_i}δp_j=0$, and $\partial_{q_j}δq_i+\partial_{p_i}δp_j=0$. The choices $δq_i=εF_{p_i}$ and $δp_i=-εF_{q_i}$ satisfy them by equality of mixed partials.