M=int(input())
D=int(input())
N=int(input())
B=int(input())
mod=27720
L=62
X=[[0]*mod for i in range(L+1)]
def f(x):
  return pow(x+D,x,mod)

for i in range(mod):
  X[0][i]=f(i)
for i in range(L):
  for j in range(mod):
    X[i+1][j]=X[i][X[i][j]]
ANS=M%mod
for i in range(L+1):
  if (N>>i)&1:
    ANS=X[i][ANS]
ANS%=B
if ANS==10:
  ANS='A'
print(ANS)