#include<iostream>
#include<string>

using namespace std;

int main(){
	string S;
	cin >> S;
	int i, Clen, Wlen;
	//cout << S << endl;
	//cout << S[2] << endl;
	//cout << S.size() << endl;
	for(i = 0; i < S.size()-1; i++){
		if(S[i] == S[i+1]){
			continue;
		}
		else{
			break;
		}
	}
	Clen = i+1;
	Wlen = S.size() - Clen;
	if(Clen - 1 >= Wlen){
		cout << Wlen << endl;
	}
	else{
		cout << Clen - 1 << endl;
	}
	return 0;
}