一本通1108

#include <bits/stdc++.h>
#define rep(i,j,n) for(register int i=j;i<=n;i++)
#define Rep(i,j,n) for(register int i=j;i>=n;i--)
#define low(x) x&(-x)
using namespace std ;
typedef long long LL ;
const int inf = INT_MAX >> 1 ;
inline LL In() { LL res(0) , f(1) ; register char c ;
#define gc c = getchar()
    while(isspace(gc)) ; c == '-' ? f = - 1 , gc : 0 ;
    while(res = (res << 1) + (res << 3) + (c & 15) , isdigit(gc)) ;
    return res * f ;
#undef gc
}

int n ;
const int N = 1000 + 5 ;
int a[N] ;
int b[N] ;
LL s(0) ;
inline void Ot() {
	n = In() ;
	rep(i,1,n) a[i] = In() ;
	rep(i,1,n) b[i] = In() ;
	rep(i,1,n) s += a[i] * b[i] ;
	cout << s << endl ;
}
signed main() {
//  freopen("test.in","r",stdin) ;
    return Ot() , 0 ;
}