题目链接
Alice has a string s. She really likes the letter “a”. She calls a string good if strictly more than half of the characters in that string are "a"s. For example “aaabb”, “axaa” are good strings, and “baca”, “awwwa”, “” (empty string) are not.

Alice can erase some characters from her string s. She would like to know what is the longest string remaining after erasing some characters (possibly zero) to get a good string. It is guaranteed that the string has at least one “a” in it, so the answer always exists.

Input
The first line contains a string s (1≤|s|≤50) consisting of lowercase English letters. It is guaranteed that there is at least one “a” in s.

Output
Print a single integer, the length of the longest good string that Alice can get after erasing some characters from s.

input
xaxxxxa

output
3

input
aaabaa

output
6

Note
In the first example, it’s enough to erase any four of the "x"s. The answer is 3 since that is the maximum number of characters that can remain.

In the second example, we don’t need to erase any characters.

题意：给你一个字符串s,判断在保持a字符的个数严格大于长度的一半的情况下，字符串的最大长度，如果a字符的个数小于长度的一半那么你可以删除任意个字符，使a字符的个数严格大于长度的一半，输出长度

题解：如果a字符的个数严格大于长度的一半的情况下，输出字符串长度，否则长度就是a字符个数 * 2 - 1

#include<bits/stdc++.h>
using namespace std;
int main(){int len,num;char str[55];scanf("%s",str);len = strlen(str);num = 0;for(int i = 0;i < len;i++)if(str[i] == 'a') num++;if(num > ceil(len * 1.0 / 2)) printf("%d\n",len);else printf("%d\n",num * 2 - 1);return 0;
}