#include<stdio.h>
int factorial(int n);
void main()
{
    int n,r,nPr,nCr,d,e,f;
    printf("Enter the value of n and then r\n\n");
 
    int factorial(int n);
    scanf("%d%d",&n,&r);
    if(n<r){
        printf("Invalid input\n");
    }
    else{
        d=factorial(n);
        e=factorial(r);
        f=factorial(n-r);
        nPr=d/f;
        nCr=d/(e*f);
        printf("\n%dP%d=%d\n\n%dC%d=%d\n",n,r,nPr,n,r,nCr);
    }
 
}
int factorial(int n)
{
    if (n<=1)
        return (1);
    else
        return(n*factorial(n-1));
}
 
 
 
 
 

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