143 人解决，178 人已尝试。
162 份提交通过，共有 407 份提交。
2.8 EMB 奖励。
单点时限: 2.0 sec
内存限制: 256 MB
Each course grade is one of the following five letters: A, B, C, D, and F. (Note that there is no grade E.) The grade A indicates superior achievement, whereas F stands for failure. In order to calculate the GPA, the letter grades A, B, C, D, and F are assigned the following grade points, respectively: 4, 3, 2, 1, and 0.
The input file will contain data for one or more test cases, one test case per line. On each line there will be one or more upper case letters, separated by blank spaces.
Each line of input will result in exactly one line of output. If all upper case letters on a particular line of input came from the set {A, B, C, D, F} then the output will consist of the GPA, displayed with a precision of two decimal places. Otherwise, the message “Unknown letter grade in input” will be printed.
A B C D F B F F C C A D C E F
2.00 1.83 Unknown letter grade in input
143 人解决，178 人已尝试。
162 份提交通过，共有 407 份提交。
2.8 EMB 奖励。