//set many funcs template #include #include #include #include #define inf 1072114514 #define llinf 4154118101919364364 #define mod 1000000007 #define pi 3.1415926535897932384 int max(int a,int b){if(a>b){return a;}return b;} int min(int a,int b){if(a= b){return (a/b)+1;}return a/b;} int ceil(int a,int b){if(a%b==0){return a/b;}return (a/b)+1;} int gcd(int a,int b){int c;while(b!=0){c=a%b;a=b;b=c;}return a;} int lcm(int a,int b){int c=gcd(a,b);a/=c;return a*b;} int nCr(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;} int fact(int a){int i,r=1;for(i=1;i<=a;i++){r*=i;}return r;} int pow(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=a;}return r;} long long llmax(long long a,long long b){if(a>b){return a;}return b;} long long llmin(long long a,long long b){if(a= b){return (a/b)+1;}return a/b;} long long llceil(long long a,long long b){if(a%b==0){return a/b;}return (a/b)+1;} long long llgcd(long long a,long long b){long long c;while(b!=0){c=a%b;a=b;b=c;}return a;} long long lllcm(long long a,long long b){long long c=llgcd(a,b);a/=c;return a*b;} long long llnCr(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;} long long llfact(long long a){long long i,r=1;for(i=1;i<=a;i++){r*=i;}return r;} long long llpow(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=a;}return r;} double dbmax(double a,double b){if(a>b){return a;}return b;} double dbmin(double a,double b){if(a*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;} int sortfnckj(const void *a,const void *b){if(*(int *)a<*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;} int llsortfncsj(const void *a,const void *b){if(*(long long *)a>*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;} int llsortfnckj(const void *a,const void *b){if(*(long long *)a<*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;} int dbsortfncsj(const void *a,const void *b){if(*(double *)a>*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;} int dbsortfnckj(const void *a,const void *b){if(*(double *)a<*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;} double calc(double x){ return 2*pi*x*x; } int main(void){ double a,b; scanf("%lf%lf",&a,&b); if(b<=0){ a*=-1; b*=-1; printf("%.12lf\n",calc(1-b)-calc(1-a)); } else if(0<=a){ printf("%.12lf\n",calc(1-a)-calc(1-b)); } else{ a*=-1; printf("%.12lf\n",calc(1)*2-calc(1-a)-calc(1-b)); } return 0; }