#include using namespace std; typedef long long signed int LL; typedef long long unsigned int LU; #define incID(i, l, r) for(int i = (l) ; i < (r); i++) #define incII(i, l, r) for(int i = (l) ; i <= (r); i++) #define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--) #define decII(i, l, r) for(int i = (r) ; i >= (l); i--) #define inc(i, n) incID(i, 0, n) #define inc1(i, n) incII(i, 1, n) #define dec(i, n) decID(i, 0, n) #define dec1(i, n) decII(i, 1, n) #define inII(v, l, r) ((l) <= (v) && (v) <= (r)) #define inID(v, l, r) ((l) <= (v) && (v) < (r)) #define PB push_back #define EB emplace_back #define MP make_pair #define FI first #define SE second #define UB upper_bound #define LB lower_bound #define PQ priority_queue #define ALL(v) v.begin(), v.end() #define RALL(v) v.rbegin(), v.rend() #define FOR(it, v) for(auto it = v.begin(); it != v.end(); ++it) #define RFOR(it, v) for(auto it = v.rbegin(); it != v.rend(); ++it) template bool setmin(T & a, T b) { if(b < a) { a = b; return true; } else { return false; } } template bool setmax(T & a, T b) { if(b > a) { a = b; return true; } else { return false; } } template bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } } template bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } } template T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); } template T lcm(T a, T b) { return a / gcd(a, b) * b; } // ---- ---- int n, a[7]; struct Frac { LL p, q; Frac() {}; Frac(LL pp, LL qq) { p = pp; q = qq; } bool operator< (const Frac & obj) const { return p * obj.q < obj.p * q; } bool operator==(const Frac & obj) const { return p * obj.q == obj.p * q; } Frac operator+ (const Frac & obj) const { return Frac(p * obj.q + obj.p * q, q * obj.q); } Frac operator- (const Frac & obj) const { return Frac(p * obj.q - obj.p * q, q * obj.q); } Frac operator* (const Frac & obj) const { return Frac(p * obj.p, q * obj.q); } Frac operator/ (const Frac & obj) const { return Frac(p * obj.q, q * obj.p); } }; bool f(Frac x[], int s) { inc(i, s) { inc(j, i) { if(x[i] == x[j]) { return true; } } } Frac y[7]; inc(i, s) { inc(j, i) { int l = 0; inc(k, s) { if(k != i && k != j) { y[l++] = x[k]; } } y[l] = x[i] + x[j]; if(f(y, s - 1)) { return true; } y[l] = x[i] - x[j]; if(f(y, s - 1)) { return true; } y[l] = x[i] * x[j]; if(f(y, s - 1)) { return true; } y[l] = x[i] / x[j]; if(f(y, s - 1)) { return true; } } } return false; } int main() { cin >> n; inc(i, n) { cin >> a[i]; } Frac x[7]; inc(i, n) { x[i] = Frac(a[i], 1); } cout << (f(x, n) ? "YES" : "NO") << endl; return 0; }