#include <stdio.h>
#include <algorithm>
using namespace std;
const long long mod = 1000000007;
int N,M,R,A[255],B[255];
long long ans = 1, prv[255][2], nxt[255][2];
int main()
{
scanf ("%d %d",&N,&M);
for (int i=0;i<N;i++) scanf ("%d %d",&A[i],&B[i]), ans = ans * (B[i] - A[i] + 1) % mod;
scanf ("%d",&R);
for (int k=0;k<=M;k++){
for (int i=0;i<R;i++) prv[i][0] = prv[i][1] = 0; prv[0][0] = 1;
for (int i=0;i<N;i++){
for (int j=0;j<R;j++) nxt[j][0] = nxt[j][1] = 0;
for (int j=0;j<R;j++){
if (A[i] < k){
int len = min(B[i],k-1) - A[i] + 1;
nxt[j][0] += prv[j][0] * len;
nxt[j][1] += prv[j][1] * len;
}
if (A[i] <= k && k <= B[i]){
nxt[j][1] += prv[j][0] + prv[j][1];
}
if (k < B[i]){
int len = B[i] - max(k+1,A[i]) + 1;
nxt[j+1][0] += prv[j][0] * len;
nxt[j+1][1] += prv[j][1] * len;
}
}
for (int j=0;j<R;j++){
prv[j][0] = nxt[j][0] % mod;
prv[j][1] = nxt[j][1] % mod;
}
}
ans = (ans + mod - prv[R-1][1]) % mod;
}
printf ("%lld\n",ans);
return 0;
}
