Roads and Cycles

There are $N$ cities numbered from $1$ to $N$. There are zero or more bidirectional routes between every pair of cities. There are total $M$ roads in the city. Each road has some cost associated with it. You are given an integer $X$ and two cities $A$ and $B$. Find the number of simple routes between cities $A$ and $B$ having cost less than or equal to $X$. A simple route is one which does n