#include <bits/stdc++.h>
using namespace std;
constexpr int BUF_SZ = 1 << 15;
inline namespace Input {
char buf[BUF_SZ];
int pos;
int len;
char next_char() {
if (pos == len) {
pos = 0;
len = static_cast<int>(fread(buf, 1, BUF_SZ, stdin));
if (!len) { return EOF; }
}
return buf[pos++];
}
int read_int() {
char ch;
int sgn = 1;
while (!isdigit(ch = next_char())) {
if (ch == '-') { sgn *= -1; }
}
int x = ch - '0';
while (isdigit(ch = next_char())) { x = x * 10 + (ch - '0'); }
return x * sgn;
}
}
inline namespace Output {
char buf[BUF_SZ];
int pos;
void flush_out() {
fwrite(buf, 1, pos, stdout);
pos = 0;
}
void write_char(const char c) {
if (pos == BUF_SZ) { flush_out(); }
buf[pos++] = c;
}
void write_int(int x) {
static char num_buf[100];
if (x < 0) {
write_char('-');
x *= -1;
}
int len = 0;
for (; x >= 10; x /= 10) { num_buf[len++] = static_cast<char>('0' + (x % 10)); }
write_char(static_cast<char>('0' + x));
while (len) { write_char(num_buf[--len]); }
write_char('\n');
}
void write_long_long(long long x) {
static char num_buf[100];
if (x < 0) {
write_char('-');
x *= -1;
}
int len = 0;
for (; x >= 10; x /= 10) { num_buf[len++] = (char) ('0' + (x % 10)); }
write_char((char) ('0' + x));
while (len) { write_char(num_buf[--len]); }
write_char('\n');
}
// auto-flush output when the program exits
void init_output() { assert(atexit(flush_out) == 0); }
}
constexpr int MOD = 1e9 + 7;
long long mul(const long long a, const long long b) {
return (a % MOD)*(b % MOD) % MOD;
}
int main() {//TODO verstehen
init_output();
int n = read_int();
vector<long long> height(n + 1, 0), width(n + 1, 0);
vector<long long> prefixSum(n + 1, 0); //Summe von der Breite
vector<long long> dp(n + 1, 0);
for (int i = 1; i <= n; ++i) {
height[i] = read_int();
}
for (int i = 1; i <= n; ++i) {
width[i] = read_int();
prefixSum[i] = (prefixSum[i - 1] + width[i]) % MOD;
}
// absteigende Höhe
stack<int> monoStack;
monoStack.push(0);
long long answer = 0;
for (int i = 1; i <= n; ++i) {
while (monoStack.size() > 1 && height[monoStack.top()] >= height[i]) {
monoStack.pop();
}
const int j = monoStack.top();
// Summe der Breiten von (j+1) .. i
const long long len = (prefixSum[i] - prefixSum[j] + MOD) % MOD;
//Summe der Breiten außer der aktuellen
const long long L1 = (len - width[i] % MOD + MOD) % MOD;
const long long triHeight = mul( mul(height[i], height[i] + 1), 500000004);
const long long triWidth = mul( mul(width[i], width[i] + 1), 500000004);
//T_A,B
const long long term1 = mul( mul(L1, triHeight), width[i] );
const long long term2 = mul(triHeight, triWidth);
const long long A = (term1 + term2) % MOD;
const long long B = mul(dp[j], width[i]);
dp[i] = ( dp[j] + mul(len, triHeight) ) % MOD;
monoStack.push(i);
answer = (answer + A + B) % MOD;
}
write_long_long(answer);
return 0;
}
