#include<bits/stdc++.h>
using namespace std;
 
int main(){
    //ios_base::sync_with_stdio(false);
 
    int counts, n, m, s[1000001], a[1000001];
 
    cin >> n >> m;
    for(int i=0; i<n; i++){cin >> s[i];}
    for(int i=0; i<m; i++){cin >> a[i];}
 
    for(int i=1; i<m; i++){
        a[i]-=a[0];
    }
	a[0]=0;
    bool found;
    counts =0;
 
    for(int i=0; i<=(n-m); i++){
        found=true;
        for(int j=i+1; j<i+m; j++){
            if((s[j]-s[i])!=a[j-i]){found=false;break;}
        }
        if(found){counts++;}
    }
 
    cout << counts;
 
    return 0;
}
 

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