pots

#include<algorithm>
#include<stdio.h>
#include<string.h>
#include<queue>
#include<stdlib.h>
using namespace std;
int A, B, C;
char a[10][10] ={ "FILL(1)","FILL(2)","DROP(1)","DROP(2)","POUR(1,2)","POUR(2,1)"};

#define maxn 510
#define INF 0x3f3f3f3f
struct point
{
    int x,y;
};
struct node
{
    int fromx,fromy,step,op;
}v[maxn][maxn];
void dfs(int x,int y)
{
    if(x==0&&y==0)
        return ;
    dfs(v[x][y].fromx,v[x][y].fromy);

    printf("%s\n",a[v[x][y].op]);
}
void bfs()
{
    queue<point>Q;
    point s,q;
    s.x = s.y = 0;
    v[0][0].step = 1;

    Q.push(s);

    while(Q.size())
    {
        s = Q.front();
        Q.pop();

        if(s.x==C||s.y==C)
        {
            printf("%d\n",v[s.x][s.y].step-1);
            dfs(s.x,s.y);

            return ;
        }
        for(int i=0;i<6;i++)
        {
            q = s;

            if(i == 0)
                q.x = A;
            else if(i == 1)
                q.y = B;
            else if(i == 2)
                q.x = 0;
            else if(i == 3)
                q.y = 0;
            else if(i == 4)
            {
                if(q.x+q.y <= B)
                    q.y += q.x, q.x = 0;//把A里面的水全倒B里面
                else
                    q.x -= (B-q.y), q.y = B;//把B倒满
            }
            else
            {
                if(q.x+q.y <= A)
                    q.x += q.y, q.y = 0;
                else
                    q.y -= (A-q.x), q.x = A;
            }

            if(v[q.x][q.y].step == 0)
            {
                v[q.x][q.y].step = v[s.x][s.y].step+1;
                v[q.x][q.y].fromx = s.x;
                v[q.x][q.y].fromy = s.y;
                v[q.x][q.y].op = i;

                Q.push(q);
            }
        }
    }
    printf("impossible\n");
}
int main()
{
    while(scanf("%d%d%d", &A,&B,&C)!=EOF)
    {
        memset(v,0,sizeof(v));
        bfs();
    }
    return 0;
}