#include <iostream>
#define _size 200
using namespace std;
int main()
{
unsigned long long tab[_size][_size];
tab[1][1] = 1;
tab[2][1] = 2;
tab[2][2] = 1;
for(int i=3;i<_size-1;i++)
{
tab[i][1] = i;
for(int j=2;j<_size-1;j++)
{
tab[i][j] = tab[i-1][j-1]+tab[i-1][j];
}
}
int x,y;
cin>>x>>y;
cout<<tab[x][y];
return 0;
}
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