#!/usr/bin/env python3


def test(cgcombis, cgcombis_orig, fixedstr=""):
    if len(cgcombis) == 0:
        return
    if len(cgcombis) == 1:
        for comb in cgcombis[0]:
            print("COMBI: " + fixedstr + comb)
    else:
        for combi in cgcombis[0]:
            fixedstr += combi
            cgcombis_new = [cgcombis[i] for i in range(1, len(cgcombis))]
            test(cgcombis_new, cgcombis_orig, fixedstr)
            fixedstr = fixedstr[:-1]
        print()


INPUT = [["1","2"],["3","4","5"],["6","7","8","9"], ["0", "1"]]
test(INPUT, INPUT)