1 #include 
     
       2 #define _for(i,a,b) for(int i = (a);i < b;i ++) 3 typedef long long ll; 4 using namespace std; 5 int rnt = 0; 6 int N,K; 7 inline ll read() 8 { 9     ll ans = 0;10     char ch = getchar(), last = ' ';11     while(!isdigit(ch)) last = ch, ch = getchar();12     while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();13     if(last == '-') ans = -ans;14     return ans;15 }16 inline void write(ll x)17 {18     if(x < 0) x = -x, putchar('-');19     if(x >= 10) write(x / 10);20     putchar(x % 10 + '0');21 }22 23 void dfs(int st,int le,int fi)24 {25     if(st==K && le>=fi)26     {27         rnt ++;28         return ;29     }30     31     _for(i,fi,le-(K-st)+1)32         dfs(st+1,le-i,i);33 }34 int main()35 {36     N = read();// sum37     K = read();// div38     dfs(1,N,1);39     write(rnt);40     return 0;41 }