{"trustable":true,"prependHtml":"\u003cstyle type\u003d\u0027text/css\u0027\u003e\n .input, .output {\n border: 1px solid #888888;\n }\n .output {\n margin-bottom: 1em;\n position: relative;\n top: -1px;\n }\n .output pre, .input pre {\n background-color: #EFEFEF;\n line-height: 1.25em;\n margin: 0;\n padding: 0.25em;\n }\n \u003c/style\u003e\n \u003clink rel\u003d\"stylesheet\" href\u003d\"//codeforces.org/s/96598/css/problem-statement.css\" type\u003d\"text/css\" /\u003e\n\u003cscript\u003e\n window.katexOptions \u003d {\n delimiters: [\n {left: \u0027$$$$$$\u0027, right: \u0027$$$$$$\u0027, display: true},\n {left: \u0027$$$\u0027, right: \u0027$$$\u0027, display: false},\n {left: \u0027$$\u0027, right: \u0027$$\u0027, display: true},\n {left: \u0027$\u0027, right: \u0027$\u0027, display: false}\n ]\n };\n\u003c/script\u003e\n","sections":[{"title":"","value":{"format":"HTML","content":"\u003cp\u003eSuppose that in a Cartesian coordinate system on an infinite plane, the x-axis represents the ground and there are n rainscreens (We don\u0027t consider their thickness.) in the sky.\u003c/p\u003e\u003cp\u003eEvery rainscreen can be described as a segment which starts from the $$$(x_1,y_1)$$$ and ends at $$$(x_2,y_2)$$$. Now if it starts to rain from the infinite high sky, I want you to tell me how many units of the x-axis will not get rained on.\u003c/p\u003e\u003cp\u003eTo simplify the problem,the rain can only move vertically whenever it falls.\u003c/p\u003e\u003cp\u003eNote that two rainscreens can overlap and intersect with each other, and there is no rainscreen which is placed vertically.\u003c/p\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cp\u003eThe first line contains one positive integer $$$n (1 \\leq n \\leq 100000)$$$.\u003c/p\u003e\u003cp\u003eEach of the next n lines contains four positive integers $$$x_1, y_1, x_2, y_2 (1 \\leq x_1 \u0026lt; x_2 \\leq 100000, 1 \\leq y_1,y_2 \\leq 100000)$$$, representing a rainscreen which starts from the $$$(x_1, y_1)$$$ and ends at $$$(x_2, y_2)$$$.\u003c/p\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cp\u003eThe only one integer - the number of units of the x-axis which will not get rained on.\u003c/p\u003e"}},{"title":"Examples","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e5\n1 2 2 1\n1 1 2 2\n3 3 4 3\n5 1 6 3\n6 3 7 2\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e4\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}},{"title":"Note","value":{"format":"HTML","content":"\u003cp\u003eConsider the example, we can draw a picture like below:\u003c/p\u003e\u003ccenter\u003e \u003cimg class\u003d\"tex-graphics\" src\u003d\"CDN_BASE_URL/b555e2bfc4b4fdc5a3072b08482d6a58?v\u003d1726235127\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\" width\u003d\"340px\"\u003e \u003c/center\u003e\u003cp\u003eIt\u0027s easy to calculate the answer is 4.\u003c/p\u003e"}}]}