diff --git a/template.cc b/template.cc
index 0bf85a1..19806a7 100644
--- a/template.cc
+++ b/template.cc
@@ -250,6 +250,7 @@ return_t qpow(ll b, ll p) {
 }
 
 #define comb(n, k) ((n) < 0 or (k) < 0 or (n) < (k) ? 0 : fact[n] / fact[k] / fact[(n) - (k)])
+#define fastcomb(n, k) ((n) < 0 or (k) < 0 or (n) < (k) ? 0 : fact[n] * factrev[k] * factrev[(n) - (k)])
 
 constexpr inline int lg2(ll x) { return x == 0 ? -1 : sizeof(ll) * 8 - 1 - __builtin_clzll(x); }