我想做50的做法，可是样例不对

#include <iostream>
#include <stack>
using namespace std;
stack<char> stk;
int l,cnt;
string s;
signed main() {
//	freopen("game.in","r",stdin);
//	freopen("game.out","w",stdout);
	cin >> l >> s;
	s=' '+s;
	for(int i=1;i<=l;++i) {
		while(!stk.empty()) stk.pop();
		for(int j=1;j<=i;++j) {
			if(!stk.empty()&&stk.top()==s[j])stk.pop();
			else stk.push(s[j]);
			if(stk.empty()&&j!=1)++cnt;
		}
	}
	cout << cnt;
	return 0;
}