## Chinese leftovers

### Problem 531

Let g(`a,n,b,m`) be the smallest non-negative solution `x` to the system:

`x = a` mod `n`

`x = b` mod `m`

if such a solution exists, otherwise 0.

E.g. g(2,4,4,6)=10, but g(3,4,4,6)=0.

Let φ(`n`) be Euler's totient function.

Let f(n,m)=g(φ(n),n,φ(m),m)

Find ∑ f(n,m) for 1000000 ≤ n < m < 1005000