That means, the count of blank cells plus cells containing "F" in range E2:E50 would total 49 for the formula to return 1, otherwise the formula would return 0.
If that is what you intend, one way to do this while foregoing an array formula could be:
=IF(COUNTIF(E2:E50,"F")+COUNTBLANK(E2:E50)=49,1,0)