#include #include #include #include #include #include using namespace std; #define mod (long)(1e9 + 7) #define all(x) (x).begin(), (x).end() #define bitcount(n) __builtin_popcountl(long(n)) #define fcout cout << fixed << setprecision(15) #define highest(x) (63 - __builtin_clzl(x)) template inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; } template inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; } template inline void POSS(T condition){ if(condition) cout << "POSSIBLE" << endl; else cout << "IMPOSSIBLE" << endl; } template inline void Poss(T condition){ if(condition) cout << "Possible" << endl; else cout << "Impossible" << endl; } template inline void First(T condition){ if(condition) cout << "First" << endl; else cout << "Second" << endl; } templateint character_count(T text, U character){ int ans = 0; for(U i: text){ ans += (i == character); } return ans; } long power(long base, long exponent, long module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ long root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }} struct position{ int y, x; }; position mv[4] = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}}; // double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); } template string to_string(pair x){ return to_string(x.first) + "," + to_string(x.second); } string to_string(string x){ return x; } template void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++) ans += to_string(*i) + " "; if(!ans.empty()) ans.pop_back(); cout << ans << endl; } template void cins(itr start, itr goal){ for(auto i = start; i != goal; i++){ cin >> (*i); } } template T gcd(T a, T b){ if(a && b){ return gcd(min(a, b), max(a, b) % min(a, b)); }else{ return a; }} template T lcm(T a, T b){ return a / gcd(a, b) * b; } struct combination{ vector fact, inv; combination(int sz) : fact(sz + 1), inv(sz + 1){ fact[0] = 1; for(int i = 1; i <= sz; i++){ fact[i] = fact[i - 1] * i % mod; } inv[sz] = power(fact[sz], mod - 2, mod); for(int i = sz - 1; i >= 0; i--){ inv[i] = inv[i + 1] * (i + 1) % mod; } } long C(int p, int q) const{ if(q < 0 || p < q) return 0; return (fact[p] * inv[q] % mod * inv[p - q] % mod); } }; int N, cnt = 0; vector> BA; long dp[2020][2020]; long buy(int now, int day){ if(now == N){ return (day != cnt) * 1e18; }else{ return min(buy(now + 1, day), buy(now + 1, day + 1) + BA[now].second + BA[now].first * day); } } int main(){ cin >> N; BA.resize(N); for(int i = 0; i < N; i++){ cin >> BA[i].second >> BA[i].first; } sort(all(BA), greater>()); int sum = 0; while(sum < N){ if(cnt % 2){ sum++; } cnt++; sum++; } memset(dp, -1, sizeof(dp)); cout << buy(0, 0) << endl; }