isleap =: monad define
	divBy4 =. 0=4|y
	divBy100 =. 0=100|y
	divBy400 =. 0=400|y
	divBy4*.divBy400+.-.divBy100
)

daysInMonth =: dyad define
	feb =. (isleap x){28 29
	y{31,feb, 31 30 31 30 31 31 30 31 30 31
)

nextMonthStart =: monad define
	('year';'month';'day') =. y
	days =. year daysInMonth month
	day =. 7 | days + day
	if. month = 11 do.
		(year+1);0;day
	else.
		year;(month+1);day
	end.
)

start =: nextMonthStart^:12 (1900;0;0)

generateMonths =: 13 : '(nextMonthStart^:y) start'

months =: generateMonths i. 1199

startedOnSunday =: 6 = [: > 2 { ]

result =: +/startedOnSunday"1 months