迷之TLE？？？

#include<iostream>
#include<cstdio>
using namespace std;
struct Node{
	int num;
	char ch;
} maxx;
string str;
bool st,fi;
int t,num[26];
inline void BIG(string &str)
{
	for(unsigned int i=0;i<str.size();++i)
		if('a'<=str[i]&&str[i]<='z')
			str[i]-=32;
}
int main(int argc, char const *argv[])
{
//	freopen("in.txt","r",stdin);
	while (true)
	{
		getline(cin,str);
		if (!st&&str=="START")
		{
			st=true;
			continue;
		}
		if (st&&str=="END")
		{
			st=false;
			continue;
		}
		if (!st&&str=="ENDOFINPUT")	break;
		if (st)
		{
			BIG(str);
			if (!fi)
			{
				for (unsigned int i=0; i<str.size(); ++i)
					if ('A'<=str[i]&&str[i]<='Z')
						if (++num[str[i]-'A']>=maxx.num)
							maxx.num=num[str[i]-'A'],maxx.ch=str[i];
				t=maxx.ch-'E';
				fi=true;
			}
			for (unsigned int i=0; i<str.size(); ++i)
				if ('A'>str[i]||str[i]>'Z')
					printf("%c",str[i]);
				else if ('A'<=str[i]&&str[i]<='Z')
					printf("%c",str[i]-t<'A'?str[i]-t+26:str[i]-t);
			printf("\n");
		}
	}
	return 0;
}