#include <stdio.h>

int main() {
   
   
    float m1 ,m2, m3, m4, m5, M;
    scanf("%f %f %f %f %f ",&m1,&m2,&m3,&m4,&m5);
    M = m1+m2=m3+m4+m5%5.0;
    printf("%f",M);
    return 0;
}