#include
int permutation(int n,int r);
int main(){
int n,r,p,c,f=1,y;
printf("n=");
scanf("%d",&n);
printf("r=");
scanf("%d",&r);
p=permutation(n,r);
if(p==0)
printf("math error");
else{
printf("P(%d,%d)=%d\n",n,r,p);
y=r;
for(;y>1;y--){
f*=y;
}
printf("C(%d,%d)=%d",n,r,p/f);}
return 0;
}
int permutation(int n,int r){
int permutation,x,y,f=1,z=1;
if(r>=0&&r<=n){
x=n;
y=(n-r);
for(;x>1;x--){
f*=x;
}
for(;y>1;y--){
z*=y;
}
return f/z;
}
else
return 0;
}