import std.conv, std.functional, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, 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)); } enum MO = 10L^^8 + 7; enum LIM = 3 * 10^^5; long[] inv, fac, invFac; void prepare() { inv = new long[LIM]; fac = new long[LIM]; invFac = new long[LIM]; inv[1] = 1; foreach (i; 2 .. LIM) { inv[i] = MO - ((MO / i) * inv[cast(size_t)(MO % i)]) % MO; } fac[0] = invFac[0] = 1; foreach (i; 1 .. LIM) { fac[i] = (fac[i - 1] * i) % MO; invFac[i] = (invFac[i - 1] * inv[i]) % MO; } } long binom(long n, long k) { if (0 <= k && k <= n) { assert(n < LIM); return fac[cast(size_t)(n)] * invFac[cast(size_t)(k)] % MO * invFac[cast(size_t)(n - k)] % MO; } else { return 0; } } long calc(int dx, int dy) { return (dx >= 0 && dy >= 0) ? binom(dx + dy, dx) : 0; } int H, W, K; int[] A, B; void main() { prepare(); try { for (; ; ) { H = readInt(); W = readInt(); K = readInt(); A = new int[K]; B = new int[K]; foreach (i; 0 .. K) { A[i] = readInt(); B[i] = readInt(); } foreach (q; 0 .. 1 << K) { Tuple!(int, "x", int, "y")[] ps; foreach (i; 0 .. K) { if ((q >> i) & 1) { ps ~= tuple!("x", "y")(A[i], B[i]); } } ps.sort; const len = cast(int)(ps.length); auto dp = new long[len]; foreach (j; 0 .. len) { dp[j] = calc(ps[j].x - 0, ps[j].y - 0); foreach (k; 0 .. j) { dp[j] -= dp[k] * calc(ps[j].x - ps[k].x, ps[j].y - ps[k].y); dp[j] %= MO; } } long ans = calc(H - 0, W - 0); foreach (k; 0 .. len) { ans -= dp[k] * calc(H - ps[k].x, W - ps[k].y); ans %= MO; } if (ans < 0) { ans += MO; } writeln(ans); } } } catch (EOFException e) { } }