RT

#include<bits/stdc++.h>
using namespace std;
long long n, m, fatigue[100000], weather[100000], f[1000][1000];
int main()
{
	scanf("%d%d", &n, &m);
	for(int i = 1; i <= n; i ++)
	 scanf("%d", &fatigue[i]);
	for(int i = 1; i <= m; i ++)
	 scanf("%d", &weather[i]);
	for(int i = 0; i <= m; i ++)
	 memset(f[i], 127, sizeof(f[i]));
	for(int i = 0; i <= m; i ++)
	 f[i][0] = 0;
	for(int i = 1; i <= m; i ++)
        for(int j = 1; j <= n && j <= i; j ++)
            f[i][j] = min(f[i - 1][j], f[i - 1][j - 1] + fatigue[j] * weather[i]);
    printf("%lld", f[m][n]);
    return 0;
}