/*
* https://mamnoonsiam.github.io/posts/joisc-2017-port-facility
*/
#include <stdio.h>
#include <stdlib.h>
#define N (1 << 20)
#define N_ (N*2)
#define M (1 << 27)
int n, a[N], b[N], aa[N_], *tt[N_ * 2], to[N_ * 2], vv[99], ll[99], rr[99], ii,
jj, nxt[M], ww[M], yy[M], head[N], ptr[N_ * 2],
qu[N], hd, tl, col[N], ans;
void link(int v, int w, int y)
{
int i;
i = ++jj;
nxt[i] = head[v];
ww[i] = w;
yy[i] = y;
head[v] = i;
}
void bilink(int v, int w, int y)
{
link(v, w, y);
link(w, v, y);
}
void pus(int i, int j)
{
int o;
o = to[i]++;
if (!o)
tt[i] = malloc(2 * sizeof **tt);
else if (0 == (o & (o - 1)))
tt[i] = realloc(tt[i], 2 * sizeof **tt * o);
tt[i][o] = j;
}
void ins(int v, int l, int r, int p, int k)
{
pus(v, k);
if (l == r)
return;
if (p <= (l + r) / 2)
ins(2 * v + 1, l, (l + r) / 2, p, k);
else
ins(2 * v + 2, (l + r) / 2 + 1, r, p, k);
}
void generate(int v, int l, int r, int x, int y)
{
if (r < x || y < l)
return;
if (x <= l && r <= y)
{
vv[ii] = v;
ll[ii] = l;
rr[ii] = r;
++ii;
return;
}
generate(2 * v + 1, l, (l + r) / 2, x, y);
generate(2 * v + 2, (l + r) / 2 + 1, r, x, y);
}
void consider(int v, int ai)
{
while (ptr[v] + 1 < to[v] && tt[v][ptr[v] + 1] < ai)
{
++ptr[v];
bilink(aa[tt[v][0]], aa[tt[v][ptr[v]]], 0);
}
}
int main()
{
int i, j;
scanf("%d", &n);
for (i = 1; i <= n; ++i)
{
scanf("%d%d", a + i, b + i);
aa[a[i]] = i;
}
for (i = 1; i <= 2 * n; ++i)
if (aa[i])
ins(0, 1, 2 * n, b[aa[i]], i);
for (i = 1; i <= n; ++i)
{
ii = 0;
generate(0, 1, 2 * n, a[i] + 1, b[i] - 1);
for (j = 0; j < ii; ++j)
{
if (0 == to[vv[j]])
continue;
if (tt[vv[j]][0] < a[i])
bilink(i, aa[tt[vv[j]][0]], 3);
consider(vv[j], a[i]);
}
}
ans = 1;
for (i = 1; i <= n; ++i)
{
if (col[i])
continue;
col[i] = 1;
hd = tl = 0;
qu[hd++] = i;
while (hd > tl)
{
int v, j;
v = qu[tl++];
for (j = head[v]; j; j = nxt[j])
{
if (0 == col[ww[j]])
{
col[ww[j]] = col[v] ^ yy[j];
qu[hd++] = ww[j];
}
else
{
if (col[ww[j]] != (col[v] ^ yy[j]))
{
puts("0");
return 0;
}
}
}
}
ans = ans * 2 % 1000000007;
}
printf("%d", ans);
return 0;
}
