#include <stdio.h> int main() { double a1,a2; char z; double fin=0; scanf("%lf%c%lf",&a1,&z,&a2); switch(z) { case '+': fin=a1+a2; printf("%0.4lf+%0.4lf=%0.4lf\n",a1,a2,fin); break; case '-': ...