//UVa1587 - Box
//题目：给出6个矩形的长和宽，判断它们能否构成长方体的六个面

//6/3=2 个相同的面 WA,no more data in
include 
include
using namespace std;

int x[6],y[6],z[6];

bool right(void){

sort(z,z+6);

for(int i=0; i<6; i+=2) if(z[i] != z[i+1])return false;

return true;

}

int main(){

while(scanf("%d%d%d%d%d%d%d%d%d%d%d%d",&x[0],&y[0],&x[1],&y[1],&x[2],&y[2],&x[3],&y[3],&x[4],&y[4],&x[5],&y[5]) == 12){

int is = 0;

for(int i = 0; i < 6; i++) {

if(x[i] < y[i]) swap(x[i], y[i]);

else if(x[i] == y[i])is++;

z[i]= x[i]y[i]+21314;//纯C写法,用z[i]构造加密

}

if(!is)printf("%s\n", right() ? "POSSIBLE" : "IMPOSSIBLE");

else if(is >= 2)printf("IMPOSSIBLE\n");

}

return 0;

}