```go
package main

import (
	"fmt"
)

func main() {
	var n int
	fmt.Scan(&n)
	
	a := make([]int64, n)
	b := make([]int64, n)
	
	for i := 0; i < n; i++ {
		fmt.Scan(&a[i])
	}
	for i := 0; i < n; i++ {
		fmt.Scan(&b[i])
	}
	
	var res int64
	for i := 0; i < n-1; i++ {
		res += a[i+1] * b[i]
	}
	fmt.Println(res)
}
```