poj 3712 Edges and More Edges

#include<cstdio>int main(){    int n,k;    while(scanf("%d%d",&n,&k),!(n==0&&k==0)) {        if(k==1) {printf("%d/n",0);continue;}        if(2*k>n) { printf("%dn",n*(n-1)>>1);continue;}        int a=0,b=0;        a=(n-1)*n/2-(n-k)*(n-k+1)/2;        if(n>(k*2)) b=(k-1)*(2*k-1);        printf("%dn",a>b?a:b);    }}