#include<bits/stdc++.h>
#define file(F) freopen(#F".in","r",stdin),freopen(#F".out","w",stdout)
#define lowbit(x) ((x)&-(x))
#define ALL(x) (x).begin(),(x).end()
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define popc(x) (__builtin_popcountll((x)))
#define abs(x) ((x)>=0?(x):-(x))
using namespace std;
using ll=long long;
using uint=uint32_t;
template<typename T>
inline bool Max(T &x,T y) { return std::less<T>()(x,y)&&(x=y,true); }
template<typename T>
inline bool Min(T &x,T y) { return std::less<T>()(y,x)&&(x=y,true); }
void Solve();
const int MOD = 1e9+7;
const int N = 2e5+25,M = 55;
int n,m;
int a[N];
ll f[N],g[N],pw[N];
int pre[M],bot[M];
int cnt[N][M];
ll ans[N];
signed main() {
#ifndef ONLINE_JUDGE
#endif
   cin.tie(nullptr)->sync_with_stdio(false);
   Solve();
}
void Solve() {
   cin>>n>>m;
   pw[0]=1; for(int i=1;i<=n;i++) pw[i]=pw[i-1]*2%MOD;
   for(ll i=1;i<=n;i++) f[i]=(2*i*i*i+3*i*i+3*i+3)%MOD;
   g[1]=f[1]; for(int i=2;i<=n;i++) g[i]=(f[i]-2*f[i-1]+f[i-2]+2*MOD)%MOD;
   for(int i=1;i<=n;i++) {
      cin>>a[i];
      pre[i]=bot[a[i]];
      bot[a[i]]=i;
      memcpy(cnt[i],cnt[i-1],sizeof cnt[i]);
      ++cnt[i][a[i]];
   } pre[n+1]=n+1;
   for(int i=1;i<=m;i++) bot[i]=n+1;
   for(int l=n;l>=1;l--) {
      vector<int> r;
      bot[a[l]]=l;
      for(int i=1;i<=m;i++) if(pre[bot[i]]<=l)
         r.emplace_back(bot[i]);
      r.emplace_back(n+1);
      sort(ALL(r));
      static bool vis[M]; memset(vis,0,sizeof vis);
      for(int i=0;i+1<r.size();i++) {
         vis[a[r[i]]]=true;
         ll res=pw[r[i]-l+1];
         for(int x=1;x<=m;x++) (res*=pw[cnt[l-1][x]+cnt[n][x]-cnt[r[i]][x]]-(!vis[x]))%=MOD;
         ans[r[i]-l+1]+=res,ans[r[i+1]-l+1]+=MOD-res;
      }
   }
   ll sum=0;
   ll iv=1;
   for(int i=1;i<=n;i++) {
      ans[i]+=ans[i-1]; ans[i]%=MOD;
      (iv*=(MOD+1)/2)%=MOD;
      sum+=ans[i]*iv%MOD*g[i]%MOD;
   }
   printf("%lld\n",sum%MOD);
}