#include <stdio.h>
#include<stdlib.h>

void nacitaj(double *a,double *b){
        scanf("%lf %lf\n",a,b);
}
double obsah(double a, double b){
        return ((a) * (b));
}
double obvod(double a, double b){
        return (2* ((a) + (b)));
}
double (*p_f)(double a, double b);
int main (void){
char c;
double *a,*b;
a=(double *) malloc(sizeof(double));
b=(double *) malloc(sizeof(double));
nacitaj(a,b);
if ((c=getchar())=='s'){
                        p_f=obsah;
        printf("%.3lf\n",p_f(*a,*b));
        }
else if (c =='o'){
     p_f=obvod;
        printf("%.3lf\n",p_f(*a,*b));
        }
getchar();
getchar();
return 0;
}