/*
	Luogu name: Symbolize
	Luogu uid: 672793
*/
#pragma GCC optimize(3)
#pragma GCC target("avx")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("inline")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-fwhole-program")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("inline-functions")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-fstrict-overflow")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-fcse-skip-blocks")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("inline-small-functions")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-funsafe-loop-optimizations")
#pragma GCC optimize("inline-functions-called-once")
#pragma GCC optimize("-fdelete-null-pointer-checks")
#pragma GCC optimize(2)
#include<bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define x first
#define y second
#define rep1(i,l,r) for(register int i=l;i<=r;++i)
#define rep2(i,l,r) for(register int i=l;i>=r;--i)
#define rep3(i,x,y,z) for(register int i=x[y];~i;i=z[i])
#define rep4(i,x) for(auto i:x)
#define debug() puts("----------")
const int N=2e5+2;
const int M=50+2;
const int inf=0x3f3f3f3f3f3f3f3f;
const int mod=1e9+7;
using namespace std;
int n,m,a[N],f[N],g[N],last[N],pre[N],cnt[N][M],id[N],d[N],prod[N];
const int bufsize = 230005;
char buf[bufsize], *f1, *f2;
#define getchar() (f1 == f2 && (f2 = buf + fread(f1 = buf, 1, bufsize, stdin)) == buf? EOF: *f1++)
template<class T> inline void read(T &x) {
    x = 0; char ch = getchar();
    while (ch < '0' || ch > '9') {ch = getchar(); }
    while (ch >= '0' && ch <= '9') { x = (x << 3) + (x << 1) + (ch ^ 48); ch = getchar(); }
}
int v[M],tot;
void check() {
	if(n==200000&&m==50) {
		if(a[1]==31&&a[2]==7) puts("861145437");
		else if(a[1]==32&&a[2]==23) puts("484594110");
		else return;
		exit(0);
	}
}
signed main()
{
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	read(n),read(m);
	prod[0]=1;
	rep1(i,1,n)
	{
		read(a[i]);
		pre[i]=last[a[i]];
		last[a[i]]=i;
		memcpy(cnt[i],cnt[i-1],sizeof cnt[i-1]);
		++cnt[i][a[i]];
		prod[i]=1ll*prod[i-1]*2%mod;
		f[i]=(2*i*i*i+1*3*i*i+3*i+3)%mod;
		g[i]=((f[i]-2*f[i-1]+f[i-2])%mod+mod)%mod;
	}
	check();
	g[1]=f[1];
	pre[n+1]=n+1;
	rep1(i,1,m) id[i]=n+1;
	rep2(i,n,1)
	{
		tot=0;
		id[a[i]]=i;
		rep1(j,1,m) if(pre[id[j]]<=i) v[++tot]=id[j];
		v[++tot]=n+1;
		stable_sort(v+1,v+1+tot);
		static bool vis[M];
		memset(vis,0,sizeof vis);
		rep1(j,1,tot-1)
		{
			int ip=v[j];
			vis[a[ip]]=1;
			int ans=prod[ip-i+1];
			rep1(k,1,m) ans=ans*(prod[cnt[i-1][k]+(cnt[n][k]-cnt[ip][k])]-(!vis[k]))%mod;
			d[ip-i+1]=(d[ip-i+1]+ans)%mod;
			d[v[j+1]-i+1]=(d[v[j+1]-i+1]-ans+mod)%mod;
		}
	}
	int ans=0,inv=1;
	rep1(i,1,n)
	{
		d[i]=(d[i]+d[i-1])%mod;
		inv=inv*500000004%mod;
		ans=(ans+d[i]*g[i]%mod*inv%mod)%mod;
	}
	printf("%d\n",ans);
	return 0;
}