#include <stdio.h>

int main() {
    char operater;
    int a = 0, b = 0, c = 0, d = 0;
    double result;
    scanf("%c %d %d %d %d", &operater, &a, &b, &c, &d);
    if (b == 0 || d == 0 || (operater == '/' && c == 0)) {
        printf("input error");
    }
    else {
        switch (operater) {
            case '+': result = (a/b)+(c/d); break;
            case '-': result = (a/b)-(c/d); break;
            case '*': result = (a/b)*(c/d); break;
            case '/': result = (a/b)/(c/d); break;
        }
        printf("%lf", result);
    }
    return 0;
}