import std.conv, std.functional, std.range, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } real readReal() { return readToken.to!real; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; } int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); } int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); } void main() { try { for (; ; ) { const N = readInt(); const D = readInt(); auto P = new int[N]; auto Q = new int[N]; foreach (i; 0 .. N) { P[i] = readInt(); Q[i] = readInt(); } auto js = iota(N).array; js.sort!((int i, int j) { const si = (Q[i] - P[i] >= 0) ? 1 : 0; const sj = (Q[i] - P[i] >= 0) ? 1 : 0; if (si != sj) return (si > sj); if (si > 0) return (P[i] < P[j]); return (Q[i] > Q[j]); }); int ans, now; foreach (i; js) { now -= P[i]; chmin(ans, now); now += Q[i]; } writeln(ans); } } catch (EOFException e) { } }