#include <bits/stdc++.h> 
using namespace std;
#define ll long long
const int N = 2e5+10;
const ll mod = 1e9+7;


ll read(){
   ll x = 0,f = 1;char c = getchar();
   for(;c < '0' || c > '9';c = getchar())if(c == '-')f = -1;
   for(;c >= '0' && c <= '9';c = getchar())x = (x<<1) + (x<<3) + c-'0';
   return x * f;
}

int n,m,t;
ll a[N],b[N],ans;
int v[310][310];
bool check(int x,int y){
    if(a[x] + b[y] < 0)return v[x][y] = 0;
    if(v[x][y] != -1)return v[x][y];
    if(x == t && y == m)return 1;
    bool f = 0;
    if(x < t)f |= check(x+1,y);
    if(y < m)f |= check(x,y+1);
    return v[x][y] = f;
}
int main(){
    freopen("expansion.in","r",stdin);
    freopen("expansion.out","w",stdout);
    n = read(),m = read();
    for(int i = 1;i <= n;i++)a[i] = read();
    for(int i = 1;i <= m;i++)b[i] = read();
    for(int j = n;j >= 1;j--){
        memset(v,-1,sizeof v);t = j;
        for(int i = j;i >= 1;i--)
            if(check(i,1))ans++;
    }
    printf("%lld\n",ans);
    
    return cerr<<clock()<<"ms"<<endl,0;
}