func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 10100;   int i, j, k, n, m, ch, c;   int s[N], t[N];   long long ans, f[N];   void R(int &x) {     x = 0;     ch = getchar();     while (ch <  0  ||  9  < ch) ch = getchar();     while ( 0  <= ch && ch <=  9 ) x = x * 10 + ch -  0 , ch = getchar();   }   void W(long long x) {     if (x >= 10) W(x / 10);     putchar(x % 10 +  0 );   }   long long min(long long x, long long y) {     if (x < y) return x;     return y;   }   int main() {     R(n);     R(c);     for (i = 1; i <= n; i++) R(s[i]);     for (i = 1; i <= n; i++) R(t[i]);     memset(f, 60, sizeof f);     f[0] = 0;     for (i = 1; i <= n; i++)       for (j = i - 1; j >= 0; j--) {         f[j + 1] = min(f[j + 1], f[j] + t[i]);         f[j] = (long long)c * j + f[j] + s[i];       }     ans = 1000000000000000000ll;     for (i = 0; i <= n; i++) ans = min(ans, f[i]);     W(ans);     puts(  );   }   