def bostan_mori(N,P,Q,MOD):
    while N>0:
        U=[0]*(len(P)+len(Q)-1)
        for i in range(len(P)):
            for j in range(len(Q)):
                if j%2==0:
                    U[i+j]+=P[i]*Q[j]
                else:
                    U[i+j]-=P[i]*Q[j]
                U[i+j]%=MOD
        P=U[N%2::2]
        V=[0]*(len(Q)*2-1)
        for i in range(len(Q)):
            for j in range(len(Q)):
                if j%2==0:
                    V[i+j]+=Q[i]*Q[j]
                else:
                    V[i+j]-=Q[i]*Q[j]
                V[i+j]%=MOD
        Q=V[0::2]
        N//=2
    return P[0]//Q[0]%MOD

p,q,r,K=map(int,input().split())
print(bostan_mori(K-1,[p,q-p,r-q-p],[1,-1,-1,-1],10))