add new file for verifythis challenge1 (not syntactically correct yet)
add new file for verifythis challenge1 (not syntactically correct yet)

ssaavedra/why3,jpdeplaix/why3,douglas-larocca/why3,douglas-larocca/why3,ssaavedra/why3,jpdeplaix/why3,ssaavedra/why3,douglas-larocca/why3,jpdeplaix/why3