func_code_string: #include <bits/stdc++.h>   using namespace std;   inline long long read() {     long long data = 0, w = 1;     char ch = 0;     while (ch !=  -  && (ch <  0  || ch >  9 )) ch = getchar();     if (ch ==  - ) w = -1, ch = getchar();     while (ch >=  0  && ch <=  9 ) data = data * 10 + ch -  0 , ch = getchar();     return data * w;   }   long long n, c, p[1000005], a[1000005];   int main() {     n = read(), c = read();     for (long long i = 1; i <= n; i++) p[i] = read();     long long sum = 0, ans = 0;     for (long long i = 1; i <= n; i++) {       long long s = read();       a[i] = s - p[i] + c * (n - i);       sum += p[i];     }     ans = sum;     sort(a + 1, a + n + 1);     for (long long i = 1; i <= n; i++)       sum += a[i] - (i - 1) * c, ans = min(ans, sum);     cout << ans <<   n ;     return 0;   }   