题目

One evening I was resting in a café. I___21___ a pair of newly bought white leather shoes, which were rather expensive. Then a boy came to me. He was in a(n) ___22___ shirt, looking pale and about eleven. No sooner had I begun to speak than he opened the ___23___ in his hand and took out the tools of shoe-polishing. He ___24___ down, took off my leather shoes, and began to shine them. He was busy doing his work ___25___ heavy rain began to pour down. People rushed to the café for ___26___ from the rain. More and more people crowded ___27___and gradually separated the boy from me. Ho已知实数x，y满足y≤xx+2y≤4y≥-2，则s=（x+1）2+（y-1）2的最大值是______．