#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define fi first
#define se second
#define eb emplace_back

using namespace std;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef vector<pii> vp;
void chmax(int &x,int y) {x=(x<y?y:x);}

int read() {
  int x=0,w=1; char c=getchar();
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+c-'0'; c=getchar();}
  return x*w;
}

const int N=5e5+5;
int n,a[N],m1,m2,m3,p1[N],p2[N],p3[N],ans,gi,gj,pa[N],pb[N],qa[N],qb[N];

namespace Brute {
  bool check(int A,int B) {
    if(A+B>min(m1,min(m2,m3))) return 0;
    rep(i,1,n) pa[i]=pb[i]=0;
    rep(i,1,A) {
      int l=p1[i], r=p3[m3-A+i];
      if(l>r) return 0;
      pa[l]=r;
    }
    rep(i,1,B) {
      int l=p3[i], r=p1[m1-B+i];
      if(l>r) return 0;
      pb[l]=r;
    }
    static int q1[N],q2[N];
    int l1=1,r1=0,l2=1,r2=0;
    rep(i,1,n) {
      if(a[i]==1) {
        if(pa[i]) q1[++r1]=pa[i];
      } else if(a[i]==3) {
        if(pb[i]) q2[++r2]=pb[i];
      } else {
        if(l1>r1&&l2>r2) continue;
        else if(l2>r2||(l1<=r1&&q1[l1]<q2[l2])) {
          if(q1[l1]<i) return 0;
          else qa[q1[l1]]=i, ++l1;
        } else {
          if(q2[l2]<i) return 0;
          else qb[q2[l2]]=i, ++l2;
        }
      }
    }
    if(l1<=r1||l2<=r2) return 0;
    return 1;
  }
  void solve() {
    int z=min(m1,min(m2,m3)), j=z;
    rep(i,0,z) {
      while(j>=0&&!check(i,j)) --j;
      if(j>=0) {
        if(ans<i+j) {
          ans=i+j;
          gi=i, gj=j;
        }
      }
    }
    printf("%d\n",ans);
    if(!ans) return;
    check(gi,gj);
    rep(i,1,n) {
      if(pa[i]) printf("%d %d %d\n",i-1,qa[pa[i]]-1,pa[i]-1);
      else if(pb[i]) printf("%d %d %d\n",i-1,qb[pb[i]]-1,pb[i]-1);
    }
  }
}

namespace Donut {
  void solve() {
    int z=min(m1,min(m2,m3)), j=z;
    for(int x=0,y=z,p=0,q=z;x<=y;) {
      int i=(x+y)>>1, j=-1;
      for(int l=p,r=q;l<=r;) {
        int w=(l+r)>>1;
        if(Brute::check(i,w)) j=w, l=w+1;
        else r=w-1; 
      }
      if(j>=0) {
        if(ans<i+j) {
          ans=i+j;
          gi=i, gj=j;
        }
      }
      if(j==-1) y=i-1;
      else if(i==0) x=i+1, q=j;
      else if(i==z) y=i-1, p=j;
      else {
        int pj=0;
        for(int l=p,r=q;l<=r;) {
          int w=(l+r)>>1;
          if(Brute::check(i-1,w)) pj=w, l=w+1;
          else r=w-1; 
        }
        if(pj>=0) {
          if(ans<i-1+pj) {
            ans=i-1+pj;
            gi=i-1, gj=pj;
          }
        }
        if(i-1+pj>i+j) y=i-1, p=j;
        else x=i+1, q=j;
      }
    }
    printf("%d\n",ans);
    if(!ans) return;
    Brute::check(gi,gj);
    rep(i,1,n) {
      if(pa[i]) printf("%d %d %d\n",i-1,qa[pa[i]]-1,pa[i]-1);
      else if(pb[i]) printf("%d %d %d\n",i-1,qb[pb[i]]-1,pb[i]-1);
    }
  }
}

signed main() {
  n=read();
  rep(i,1,n) a[i]=read();
  rep(i,1,n) {
    if(a[i]==1) p1[++m1]=i;
    else if(a[i]==2) p2[++m2]=i;
    else p3[++m3]=i;
  }
  if(n<=10000) {
    Brute::solve();
    return 0;
  }
  Donut::solve();
  return 0;
}