import std.algorithm, std.conv, std.range, std.stdio, std.string; const mod = 10 ^^ 9 + 7; alias FactorRing!(mod, true) mint; void main() { auto n = readln.chomp.to!int; if (n == 1) { writeln(1); return; } auto dp = new mint[][][][](n+1, n+1, 2, 2); dp[2][0][0][0] = mint(2); foreach (i; 3..n+1) foreach (j; 0..i) { auto v11 = dp[i-1][j][1][1]; if (v11 > 0) { dp[i][j][1][1] += v11; // split x-1,x-3 dp[i][j-1][0][0] += v11; // split x,x-2 dp[i][j-1][1][0] += v11 * (j-2); // split other dp[i][j+1][1][1] += v11; // add next x-1 dp[i][j][1][0] += v11 * (i-j-1); } auto v01 = dp[i-1][j][0][1]; if (v01 > 0) { dp[i][j-1][0][0] += v01; // split x,x-2 dp[i][j-1][1][0] += v01 * (j-1); // split other dp[i][j+1][1][1] += v01 * 2; // add next x-1 dp[i][j][1][0] += v01 * (i-j-2); } auto v10 = dp[i-1][j][1][0]; if (v10 > 0) { dp[i][j][0][1] += v10; // split x-1,x-3 dp[i][j-1][0][0] += v10 * (j-1); // split other dp[i][j+1][0][1] += v10; // add next x-1 dp[i][j][0][0] += v10 * (i-j-1); } auto v00 = dp[i-1][j][0][0]; if (v00 > 0) { if (j > 0) dp[i][j-1][0][0] += v00 * j; // split dp[i][j+1][0][1] += v00 * 2; // add next x-1 dp[i][j][0][0] += v00 * (i-j-2); } } writeln(dp[n][0][0][0]); } struct FactorRing(int m, bool pos = false) { version(BigEndian) { union { long vl; struct { int vi2; int vi; } } } else { union { long vl; int vi; } } @property int toInt() { return vi; } alias toInt this; this(int v) { vi = v; } this(int v, bool runMod) { vi = runMod ? mod(v) : v; } this(long v) { vi = mod(v); } ref FactorRing!(m, pos) opAssign(int v) { vi = v; return this; } pure auto mod(int v) const { static if (pos) return v % m; else return (v % m + m) % m; } pure auto mod(long v) const { static if (pos) return cast(int)(v % m); else return cast(int)((v % m + m) % m); } static if (m < int.max / 2) { pure auto opBinary(string op: "+")(int rhs) const { return FactorRing!(m, pos)(mod(vi + rhs)); } pure auto opBinary(string op: "-")(int rhs) const { return FactorRing!(m, pos)(mod(vi - rhs)); } } else { pure auto opBinary(string op: "+")(int rhs) const { return FactorRing!(m, pos)(mod(vl + rhs)); } pure auto opBinary(string op: "-")(int rhs) const { return FactorRing!(m, pos)(mod(vl - rhs)); } } pure auto opBinary(string op: "*")(int rhs) const { return FactorRing!(m, pos)(mod(vl * rhs)); } pure auto opBinary(string op)(FactorRing!(m, pos) rhs) const if (op == "+" || op == "-" || op == "*") { return opBinary!op(rhs.vi); } static if (m < int.max / 2) { auto opOpAssign(string op: "+")(int rhs) { vi = mod(vi + rhs); } auto opOpAssign(string op: "-")(int rhs) { vi = mod(vi - rhs); } } else { auto opOpAssign(string op: "+")(int rhs) { vi = mod(vl + rhs); } auto opOpAssign(string op: "-")(int rhs) { vi = mod(vl - rhs); } } auto opOpAssign(string op: "*")(int rhs) { vi = mod(vl * rhs); } auto opOpAssign(string op)(FactorRing!(m, pos) rhs) if (op == "+" || op == "-" || op == "*") { return opOpAssign!op(rhs.vi); } }