// URL: https://yukicoder.me/problems/no/786 import std.algorithm, std.container, std.math, std.range, std.typecons, std.string; version(unittest) {} else void main() { int n; io.getV(n); auto dp = new long[](n+1); dp[0] = 1; dp[1] = 1; foreach (i; 2..n+1) dp[i] = dp[i-1]+dp[i-2]; io.put(dp[n]); } auto io = IO(); struct IO { import std.algorithm, std.conv, std.format, std.meta, std.range, std.stdio, std.traits; dchar[] buf; auto sp = (new dchar[](0)).splitter; int precision = 10; string delimiter = " "; void nextLine() { stdin.readln(buf); sp = buf.splitter; } auto get(T)(ref T v) { if (sp.empty) nextLine(); v = sp.front.to!T; sp.popFront(); } auto getV(T...)(ref T v) { foreach (ref w; v) get(w); } auto getA(T)(size_t n, ref T v) if (hasAssignableElements!T) { v = new T(n); foreach (ref w; v) get(w); } auto getC(T...)(size_t n, ref T v) if (allSatisfy!(hasAssignableElements, T)) { foreach (ref w; v) w = new typeof(w)(n); foreach (i; 0..n) foreach (ref w; v) get(w[i]); } auto getM(T)(size_t r, size_t c, ref T v) if (hasAssignableElements!T && hasAssignableElements!(ElementType!T)) { v = new T(r); foreach (ref w; v) getA(c, w); } auto putA(T)(T v) { static if (isInputRange!T && hasLength!T && !isSomeString!T) { foreach (i, w; v) { putA(w); if (i < v.length - 1) write(delimiter); } } else if (isFloatingPoint!T) { writef(format("%%.%df", precision), v); } else { write(v); } } auto put(T...)(T v) { foreach (i, w; v) { putA(w); if (i < v.length - 1) write(delimiter); } writeln; } auto putB(S, T)(bool c, S t, T f) { if (c) put(t); else put(f); } auto dbg(T...)(T v) { stderr.writeln(v); } }