#include using namespace std; #define fs first #define sc second #define pb push_back #define mp make_pair #define eb emplace_back #define ALL(A) A.begin(),A.end() #define RALL(A) A.rbegin(),A.rend() typedef long long LL; typedef pair P; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } template T gcd(T a,T b){return b?gcd(b,a%b):a;} const LL mod=1000000007; const LL LINF=1LL<<60; const int INF=1<<30; int dx[]={1,0,-1,0,1,-1,1,-1}; int dy[]={0,1,0,-1,1,-1,-1,1}; vector fact; vector inver(1000001); LL combi(int n,int r){ if(n 0){ if(n&1){ x=x*a%mod; } a=a*a%mod; n >>= 1; } return x; } void set_combi(){ LL s=1; fact.push_back(1); for(int i=1;i<=1000000;i++){ s*=i; s%=mod; fact.push_back(s); } inver[1000000]=fpow(fact[1000000],mod-2); for(int i=999999;i>=0;i--){ inver[i]=inver[i+1]*(i+1)%mod; } } int main(){ set_combi(); LL a,b,c;cin >> a >> b >> c; LL n = a + b + c; vector p(n + 1, 0); vector cnt(n + 1, 0); for (int i = c; i <= n-2; i++) { LL t = (combi(n - c - 1, b) - combi(i - c, b) + mod)%mod; cnt[i - 1] = combi(i - 1, c - 1) * t %mod; if(i - 2 >= 0) p[i - 2] = combi(i - 2, c - 2) * t %mod; } for (int i = n-1; i >= 0; i--) { p[i] = (p[i] + p[i+1])%mod; cnt[i] = (cnt[i] + p[i])%mod; } LL ans = 0; for (int i = 0; i < n; i++) { ans = (ans + cnt[i] * fpow(2, i))%mod; } cout << ans << endl; return 0; }