#include<sstream> #include<iostream> #include<cstdio> #include<cstdlib> #include<cstring> #include<cmath> #include<string> #include<vector> #include<set> #include<map> #include<queue> #include<numeric> #include<functional> #include<algorithm> #include<bitset> using namespace std; #define INF (1<<29) #define rep(i,n) for(int i=0;i<(int)(n);i++) #define all(v) v.begin(),v.end() #define uniq(v) v.erase(unique(all(v)),v.end()) #define indexOf(v,x) (find(all(v),x)-v.begin()) #define MOD 1000000007 int main(){ int n,s,k; cin>>n>>s>>k; s-=(n-1)*k*n/2; if(s<0){ cout<<0<<endl; return 0; } vector<int> dp(s+1,0); dp[0]=1; for(int i=1;i<=n;i++){ rep(j,s-i+1){ dp[j+i]+=dp[j]; dp[j+i]%=MOD; } } cout<<dp[s]<<endl; return 0; }