//

 //by coolxxx

 //#include<bits/stdc++.h>

 #include<iostream>

 #include<algorithm>

 #include<string>

 #include<iomanip>

 #include<map>

 #include<stack>

 #include<queue>

 #include<set>

 #include<bitset>

 #include<memory.h>

 #include<time.h>

 #include<stdio.h>

 #include<stdlib.h>

 #include<string.h>

 //#include<stdbool.h>

 #include<math.h>

 #define min(a,b) ((a)<(b)?(a):(b))

 #define max(a,b) ((a)>(b)?(a):(b))

 #define abs(a) ((a)>0?(a):(-(a)))

 #define lowbit(a) (a&(-a))

 #define sqr(a) ((a)*(a))

 #define swap(a,b) ((a)^=(b),(b)^=(a),(a)^=(b))

 #define mem(a,b) memset(a,b,sizeof(a))

 #define eps (1e-8)

 #define J 10

 #define mod 1000000007

 #define MAX 0x7f7f7f7f

 #define PI 3.14159265358979323

 #define N 104

 using namespace std;

 typedef long long LL;

 int cas,cass;

 int n,m,lll,ans;

 int a[N],b[N],c[N];

 bool work()

 {

     int i,j,sum=;

     for(i=;i<=n;i++)

     {

         sum-=a[i];

         if(sum<)return ;

         sum+=b[i];

         if(sum>m)return ;

         if(c[i]> && sum!=m)return ;

     }

     if(b[n]!= || c[n]!= || sum!=)return ;

     return ;

 }

 int main()

 {

     #ifndef ONLINE_JUDGE

 //    freopen("1.txt","r",stdin);

 //    freopen("2.txt","w",stdout);

     #endif

     int i,j,k;

 //    for(scanf("%d",&cass);cass;cass--)

 //    for(scanf("%d",&cas),cass=1;cass<=cas;cass++)

 //    while(~scanf("%s",s+1))

     while(~scanf("%d",&m))

     {

         scanf("%d",&n);

         ans=;

         for(i=;i<=n;i++)

             scanf("%d%d%d",&a[i],&b[i],&c[i]);

         if(work())puts("possible");

         else puts("impossible");

     }

     return ;

 }

 /*

 //

 //

 */