LG5204

#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long

template<typename T>
inline void read(T&x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int p=1e9+7;
const int N=1e5+7;

inline ll qpow(ll a,ll b){
    ll ans=1;
    while(b){
        if(b&1)(ans*=a)%=p;
        (a*=a)%=p;
        b>>=1;
    }
    return ans;
}

inline int sub(int a,int b){
    return (a-=b)<0?a+p:a;
}

int n,k;
int f[N];
int c[N];

inline ll solve(int c,int len){
    ll x=1e9-c;
    ll t=qpow(x,k);
    f[0]=1;
    for(int i=1;i<=len;++i){
        f[i]=(x+1)*f[i-1]%p;
        if(i>=k)f[i]=sub(f[i],t*(i==k?1:f[i-k-1])%p);
    }
    return f[len];
}

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    r(n),r(k);
    for(int i=1;i<=n-k+1;++i){
        r(c[i]);
    }
    ll ans=1;
    for(int i=1,j;i<=n-k+1;i=j+1){
        for(j=i;c[j+1]==c[j];++j);
        int len=j-i+k;
        if(i!=1&&c[i]<c[i-1])len-=k;
        if(j!=n-k+1&&c[j]<c[j+1])len-=k;
        if(len<-1){
            ans=0;
            break;
        }
        if(len>0)ans=ans*solve(c[i],len)%p;
    }
    printf("%lld\n",ans);
}