function twoLines(a,b,c,d,t) {
	let l1o = b - a
	let l2o = d - c
	let r = 0
	for(let l1=1;l1<=l1o;l1++) { 
		for(let i=0;i<=(l1o-l1);i++) {
			let a_ = a + i
			let b_ = a_ + l1
			let l2 = (l1o + l2o - l1)
			for(let c_ = Math.max(b_ + 1, c - (l2 - l2o)); c_<=c && c_+l2<=t;c_++) {
				let d_ = c_ + l2
				//console.log(`${a_}--${b_} (${b_-a_}) ${c_}--${d_} (${d_ - c_})`)
				r++
			}
		}
	}
	return r
}
let mul = 1500
let abcd = Array.from({length:4}).map((e,i) => Math.floor(mul * i + Math.random()*mul))
let r = twoLines(...abcd,mul*4)
console.log(`a,b,c,d = ${abcd.join(',')} -> ${r} перестановок`)

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