#define ll long long#define maxn 1000010#define MOD 1000000007ll f[maxn],ny[maxn];ll inv(ll a,ll m){ll p=1,q=0,b=m,c,d;while(b>0){c=a/b;d=a; a=b; b=d%b;d=p; p=q; q=d-c*q;}return p<0?p+m:p;}void init(){f[0]=1;ny[0]=inv(f[0],MOD);for(int i=1;i<maxn;++i){f[i]=f[i-1]*i%MOD;ny[i]=inv(f[i],MOD);}}ll C(ll a,ll b){if(b<0 || a<0 || a<b) return 0;return f[a]*ny[b]%MOD*ny[a-b]%MOD;}ll ans=C(p,q);
，看了哪些风景，遇到哪些人。尽管同学说，
