#include <stdio.h>
#define DEBUGe

#define NOP do{}while(0)

#ifdef DEBUG
#define TRACE(...) do{printf(__VA_ARGS__);fflush(stdout);}while(0)
#define TRACECR do{printf("\n");fflush(stdout);}while(0)
#else
#define TRACE(...) NOP
#define TRACECR NOP
#endif
#define REP(a,b) for(int a=0;a<(b);++a)
int main( void ) {
    int aa,bb,cc;
    //int minval = 2147483647;
    //int maxval = -2147483648;
    double val,pp,qq,rr;

    scanf("%d %d %d", &aa, &bb, &cc );
    if( ( aa >= bb )&&( aa >= cc ) ) {
        pp = aa;
        if( bb >= cc ) {
            qq = bb;
            rr = cc;
        } else {
            qq = cc;
            rr = bb;
        }
    } else if( ( bb >= aa )&&( bb >= cc ) ) {
        pp = bb;
        if( aa >= cc ) {
            qq = aa;
            rr = cc;
        } else {
            qq = cc;
            rr = aa;
        }
    } else {
        pp = cc;
        if( aa >= bb ) {
            qq = aa;
            rr = bb;
        }
    }

   printf("%.12f\n", (pp+qq)/(pp+qq+rr) );

    return 0;
}