#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N=1e2+5,K=N*N;
const LL INF=1ll<<60;
int n,k,a[K],m,b[N],pos[N],cnt[N];
LL dis[N];
struct Edge
{
    int u,v;
    LL w;
};
vector<Edge>ans;

namespace SPJ {
    struct atom {
        int x;
        long long w;
        atom(int _x = 0, long long _w = 0) {
        x = _x;
        w = _w;
        }
    };
    bool SPFA(int *target, int K, int N, vector<Edge> EdgeSet) {
        static long long dis[105];
        static bool inq[105];
        static vector<atom> go[105];
        static int q[114514];

        for (int i = 0; i < EdgeSet.size(); i++) {
        go[EdgeSet[i].u].push_back(atom(EdgeSet[i].v, EdgeSet[i].w));
        }

        for (int i = 1; i <= N; i++) inq[i] = 0, dis[i] = 1ll << 60;
        int t = 1;
        q[t] = 1;
        dis[1] = 0;
        inq[1] = 1;

        if (target[1] != 1) return 0;

        for (int i = 1; i <= t; i++) {
        int x = q[i];
        for (auto w : go[x]) {
            int y = w.x;
            if (dis[y] > dis[x] + w.w) {
            dis[y] = dis[x] + w.w;
            if (!inq[y]) {
                inq[y] = 1;
                q[++t] = y;
                if (t > K) return 0;
                if (q[t] != target[t]) {
                return 0;
                }
            }
            }
        }
        inq[x] = 0;
        }
        return t == K;
    }
};	// namespace SPJ
signed main()
{
    ios::sync_with_stdio(false),cin.tie(nullptr);
    cin>>n>>k;
    for(int i=1;i<=k;++i)
        cin>>a[i];
    for(int i=2;i<=k;++i)
        if(a[i]==1||a[i-1]==a[i])
            return cout<<"No\n",0;
    for(int i=1;i<=k;++i)
        pos[a[i]]=i;
    for(int i=1;i<=k;++i)
        if(pos[a[i]]==i)
            b[++m]=a[i];
    // cout<<"m:"<<m<<"\n";
    // cout<<"b:\n";
    // for(int i=1;i<=m;++i)
    //		 cout<<b[i]<<" \n"[i==m];
    // cout<<"pos:\n";
    // for(int i=1;i<=n;++i)
    //		 cout<<pos[i]<<" \n"[i==n];
    for(int i=1;i<=m-1;++i)
    {
        int l=pos[b[i]]+1,r=pos[b[i+1]]-1;
        for(int j=l;j<=r;++j)
            if(++cnt[a[j]]>=2) // 出点都是 a[l]，所以在 SPFA 过程中不可以入两次队
                return cout<<"No\n",0;
        for(int j=l;j<=r;++j)
            cnt[a[j]]=0;
    }
    for(int i=1;i<=n;++i)
        dis[i]=INF;
    int nowdis=0; // 当前 a[l] 的 dis (吗)
    for(int i=1;i<=m-1;++i)
    {
        int l=pos[b[i]]+1,r=pos[b[i+1]]-1;
        for(int j=l;j<=r;++j)
        {
            --dis[a[j]]; // 想要被更新，距离至少得 -1
            ans.push_back({b[i],a[j],dis[a[j]]-nowdis});
        }
        nowdis+=INF-dis[b[i]];
        // cout<<"nowdis: "<<nowdis<<"\n";
        // cout<<"dis:\n";
        // for(int j=1;j<=n;++j)
        //		 cout<<dis[j]<<" \n"[j==n];
        ans.push_back({b[i],b[i+1],INF-dis[b[i]]}); // 不是最优点不更新后面
    }
    if(SPJ::SPFA(a,k,n,ans))
    {
        cout<<"Yes\n"<<ans.size()<<"\n";
        for(auto [u,v,w]:ans)
            cout<<u<<" "<<v<<" "<<w<<"\n";
    }
    else
        cout<<"No\n";
    return 0;
}