Codeforces 339E

#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <ctime>
#include <set>
#include <map>
using namespace std;

const int maxn=1100;

struct point
{
    int x, y;
};

int n;
int sum;
int a[maxn], des[maxn];
point ans[10];

void init()
{
    scanf("%d", &n);
    a[0]=0; a[n+1]=n+1;
    for (int i=1; i<=n; ++i) scanf("%d", &a[i]);
}
void rev(int le, int ri)
{
    for (int i=le; i<=(ri+le)/2; ++i)
        swap(a[i], a[ri-(i-le)]);
}
bool check()
{
    for (int i=1; i<=n; ++i)
        if (a[i]!=i) return false;
    return true;
}
void print(int step)
{
    printf("%d
", step);
    for (int i=step; i>0; --i)
        printf("%d %d
", ans[i].x, ans[i].y);
    exit(0);
}
void dfs(int k)
{
    if (check()) print(k-1);
    if (k>3) return;
    for (int i=1; i<n; ++i)
        for (int j=i+1; j<=n; ++j)
            if (abs(a[i-1]-a[j])==1 || abs(a[i]-a[j+1])==1)
            {
                ans[k].x=i;
                ans[k].y=j;
                rev(i, j);
                dfs(k+1);
                rev(i, j);
            }
}
int main()
{
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    init();
    dfs(1);
    return 0;
}