#include<stdio.h>
#include<math.h>
int main(void){
   int n,m;
   scanf("%d,%d",&n,&m);
   if(n==m){
    printf("%.7lf\n",sqrt(n*n+m*m));
   }else if(n>m){
       printf("%.7lf\n",sqrt(n*n-m*m));
   }else if(m>n){
        printf("%.7lf\n",sqrt(m*m-n*n));
   }
return 0;
}