Imagine that we have 49 cards with the values written on their faces, (they are all visible ) as follows; $$25, 24, 23, 22, ........3, 2, 1, 2, 3, .........23, 24, 25$$
suppose Paola and Victor are choosing cards from this line sequentially. Paola is making the first choice and Victor is following her and they continue sequentially. Notice that they can choose the card from any position.
Show that Paola has a simple strategy which guarantees exactly a sum (sum of the values written on the faces of the cards she collects) equals to that of Victor plus one.
Paola's strategy is simple:
On the first turn, pick $1$.
On any subsequent turn, if Victor chooses $n$, choose $n$.
Since there are exactly two copies of each integer $n \ne 1$, the above specifications describe her strategy completely, and at the end of the game, Paola has exactly those integers Victor picked, in addition to the $1$ she picked at the start, so her sum is Victor's plus one.
Perhaps there is more to this game you have to stated.