func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 1e5 + 50;   long long a[MAXN], b[MAXN], dp[MAXN];   long long la[MAXN], lb[MAXN];   int sz, cur, n;   double cross(int x, int y) { return (double)(lb[x] - lb[y]) / (la[y] - la[x]); }   void newLine(long long p, long long q) {     la[sz] = p;     lb[sz] = q;     while (sz > 1 && cross(sz - 1, sz - 2) > cross(sz, sz - 1)) {       la[sz - 1] = la[sz];       lb[sz - 1] = lb[sz];       sz--;     }     sz++;   }   long long find(long long x) {     while (cur + 1 < sz && x > cross(cur, cur + 1)) cur++;     return la[cur] * x + lb[cur];   }   int main() {     scanf( %d , &n);     for (int i = 1; i <= n; i++) cin >> a[i];     for (int i = 1; i <= n; i++) cin >> b[i];     dp[1] = 0;     newLine(b[1], 0);     for (int i = 2; i <= n; i++) {       dp[i] = find(a[i]);       newLine(b[i], dp[i]);     }     cout << dp[n];   }   