#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<ll>;
using pll = pair<ll,ll>;
using vpl = vector<pll>;
using vvl =vector<vll>;
#define f first
#define s second
#define pb push_back
#define all(v) v.begin(),v.end()
void fuck(){
cout << "impossible";
exit(0);
}
vll op, dp;
struct seg{
ll n;
vll bl;
ll mx(ll a, ll b){
if(dp[a])return a;
return b;
}
seg(ll n):n(n){
bl = vll(n*2);
}
void upd(ll i, ll x){
for(i+=n; i>0; i/=2){
bl[i] = mx(bl[i],x);
}
}
ll qu(ll a, ll b){
ll ans=bl[a+n];
for(a+=n,b+=n;a<=b; a/=2, b/=2){
if(a%2==1)ans = mx(ans, bl[a++]);
if(b%2==0)ans = mx(ans, bl[b--]);
}
return ans;
}
};
int main(){
ios_base::sync_with_stdio(0);cin.tie(NULL);
ll n, m;
cin >> n >> m;
vpl rl(m);
vll po(n+2);
ll st=0;
for(ll j = 0; j < m; ++j){
pll& i = rl[j];
cin >> i.f >> i.s;
i.f--;
i.s--;
if(i.f==0)st=j;
if(i.f<=i.s){
po[i.f]++;
po[i.s+1]--;
}
else{
st=j;
po[0]++;
po[i.s+1]--;
po[i.f]++;
i.s+=n;
}
}
vll am(n);
am[0]=po[0];
vll one={-1};
if(am[0]==1)fuck();
else if(am[0]==2)one.pb(0);
for(ll i = 1; i < n; ++i){
am[i]=am[i-1]+po[i];
if(am[i]==1)fuck();
else if(am[i]==2)one.pb(i);
}
if(one.size()>1)one.pb(one[1]+n);
one.pb(1e9);
op = dp = vll(m);
vll ord(m);
ll N = 1<<(32-__builtin_clz(n*2-1));
seg *S = new seg(N);
iota(all(ord),0);
sort(all(ord), [&](ll a, ll b){return rl[a].f>rl[b].f;});
ll lm = one[lower_bound(all(one), rl[st].f)-one.begin()];
for(ll i:ord){
if(i==st)continue;
if(rl[i].s>=lm)continue;
if(rl[i].s>=rl[st].f-1){dp[i]=1;op[i]=st;}
else{
ll bt = max(rl[i].f,one[upper_bound(all(one), rl[i].s)-one.begin()-1]+1);
if(bt>rl[i].s+1)continue;
ll nx = S->qu(bt, rl[i].s+1);
dp[i]=dp[nx];
op[i]=nx;
}
S->upd(rl[i].f, i);
}
if(rl[st].s==rl[st].f+n-1){dp[st]=1;op[st]=st;}
else{
ll bt = max(0ll,one[upper_bound(all(one), rl[st].s-n)-one.begin()-1]+1);
if(bt<=rl[st].s-n+1){
ll nx = S->qu(bt, rl[st].s-n+1);
if(dp[nx]==1){
dp[st]=dp[nx];
op[st]=nx;
}
}
if(bt==0){
bt = max(rl[st].f,one[upper_bound(all(one), n-1)-one.begin()-1]+1);
if(bt<=n-1){
ll nx = S->qu(bt, n-1);
if(dp[nx]==1){
dp[st]=dp[nx];
op[st]=nx;
}
}
}
}
vll ans(m);
if(!dp[st])fuck();
ans[st]=1;
ll cur = op[st];
while(cur!=st){
ans[cur]=1;
cur=op[cur];
}
for(ll i:ans)cout << i;
}
