#include<bits/stdc++.h>
using namespace std;

#define pb push_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
const int maxn = 1e3 + 70;
const int INF = 0x3f3f3f3f;
const ll inf = 0x3f3f3f3f3f3f3f3f;
const int MOD = 1e9 + 7;
const double eps = 1e-7;
const double PI = acos(-1.0);

int n, m;

ll dp[2][maxn][11];

bool ok[2][maxn][11];

int main(){
    //freopen("in.txt", "r", stdin);
    int T; cin>>T;
    while(T--){
        cin>>n>>m;
        bool t = 0;
        memset(dp[t],0,sizeof(dp[t]));
        memset(ok[t],0,sizeof(ok[t]));
        dp[t][0][0] = 1; ok[t][0][0] = true;
        for(int i=1;i<=n;i++){
            for(int j=0;j<=m;j++){
                dp[t^1][j][0] = 0; ok[t^1][j][0] = 0;
                for(int l=0;l<=10;l++){
                    dp[t^1][j][0] = (dp[t^1][j][0]+dp[t][j][l])%MOD;
                    ok[t^1][j][0] |= ok[t][j][l];
                }
                for(int k=1;k<=10;k++){
                    dp[t^1][j][k]=dp[t][j-1][k-1]*(i-1)%MOD;
                    ok[t^1][j][k]=ok[t][j-1][k-1]&&(i!=1);
                }
            }
            t ^= 1;
        }
        printf("%lld\n",ok[t][m][0]?dp[t][m][0]:-1);
    }
    return 0;
}