#include <stdio.h>
#include <string.h>
#define N 100000
#define M 100000
int max(int a, int b) { return a > b ? a : b; }
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
int ll[M], rr[M];
void sort(int *hh, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, h = hh[l + rand_() % (r - l)], tmp;
while (j < k)
if (ll[hh[j]] == ll[h])
j++;
else if (ll[hh[j]] < ll[h]) {
tmp = hh[i], hh[i] = hh[j], hh[j] = tmp;
i++, j++;
} else {
k--;
tmp = hh[j], hh[j] = hh[k], hh[k] = tmp;
}
sort(hh, l, i);
l = k;
}
}
int main() {
static int kk[N * 2 + 1], hh[M], hh_[N * 2], ii[M], qu[M];
static char ans[M + 1];
int n, m, h, h_, i, cnt, cnt_, tmp;
scanf("%d%d", &n, &m);
h_ = 0;
for (h = 0; h < m; h++) {
scanf("%d%d", &ll[h], &rr[h]), ll[h]--, rr[h]--;
if (h_ == -1 || (rr[h_] - ll[h_] + n) % n < (rr[h] - ll[h] + n) % n)
h_ = h;
}
for (h = 0; h < m; h++)
if (h != h_)
ll[h] = (ll[h] - ll[h_] + n) % n, rr[h] = (rr[h] - ll[h_] + n) % n;
rr[h_] = (rr[h_] - ll[h_] + n) % n, ll[h_] = 0;
for (h = 0; h < m; h++) {
if (rr[h] < ll[h])
rr[h] += n;
kk[ll[h]]++, kk[rr[h] + 1]--;
}
for (i = 1; i < n * 2; i++)
kk[i] += kk[i - 1];
for (i = 0; i < n; i++) {
if (kk[i] + kk[n + i] < 2) {
printf("impossible\n");
return 0;
}
kk[i] = kk[n + i] = kk[i] + kk[n + i] == 2;
}
for (i = 1; i < n * 2; i++)
kk[i] += kk[i - 1];
for (h = 1; h < m; h++)
hh[h] = h;
hh[0] = h_, hh[h_] = 0;
sort(hh, 1, m);
memset(hh_, -1, n * 2 * sizeof *hh_);
ii[0] = -1, hh_[rr[h_]] = h_;
for (h = 1, i = 0; h < m; h++) {
h_ = hh[h];
while (i < n + n && (i + 1 < ll[h_] || hh_[i] == -1))
i++;
if (i < rr[h_] && kk[i] - (ll[h_] == 0 ? 0 : kk[ll[h_] - 1]) == 0)
ii[h_] = i, hh_[rr[h_]] = h_;
else
ii[h_] = -1;
}
for (i = -1; i < n - 1; i++) {
if (hh_[n + i] != -1)
break;
if (i <= rr[0] && kk[n + 1 + i] - kk[n + i] > 0) {
i = n - 1;
break;
}
}
if (i == n - 1) {
printf("impossible\n");
return 0;
}
h = hh_[n + i];
cnt = 0;
while (h != hh[0])
qu[cnt++] = h, h = hh_[ii[h]];
qu[cnt++] = h;
for (h = 0, h_ = cnt - 1; h < h_; h++, h_--)
tmp = qu[h], qu[h] = qu[h_], qu[h_] = tmp;
cnt_ = 0;
for (h = 0; h < cnt; h++) {
while (cnt_ > 1 && ll[qu[h]] < rr[qu[cnt_ - 2]] + 1)
cnt_--;
qu[cnt_++] = qu[h];
}
cnt = cnt_;
h = 0;
while (h + 1 < cnt && ll[qu[h + 1]] < rr[qu[cnt - 1]] - n + 1)
h++;
memset(ans, '0', m * sizeof *ans);
while (h < cnt)
ans[qu[h++]] = '1';
printf("%s\n", ans);
return 0;
}
