Box 1 contains three cards bearing numbers $1,2,3$; box 2 contains five cards bearing numbers $1,2,3$, 4,5 ; and box 3 contains seven cards bearing numbers $1,2,3,4,5,6,7$. A card is drawn from each of the boxes. Let x be the number on the card drawn from the $\mathrm{i}^{\text {th }}$ box, $\mathrm{i}=1,2,3$.

The probability that $x_1+x_2+x_3$ is odd, is