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53 lines
1.3 KiB
C++

#define _CRT_SECURE_NO_WARNINGS
#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
#include <bits/stdc++.h>
using namespace std;
#define CRP(t, x) const t &x
#define OPL(t, x) bool operator<(CRP(t, x)) const
#define FIL(x, v) memset(x, v, sizeof(x))
#define CLR(x) FIL(x, 0)
#define NE1(x) FIL(x, -1)
#define INF(x) FIL(x, 0x3f)
#ifndef _DEBUG
#define _DEBUG 0
#endif // !_DEBUG
#define IFD if (_DEBUG)
typedef long long ll, i64;
const int N = 1e5 + 50;
char s[N];
int main()
{
scanf("%s", s);
int n = strlen(s), ans = 0;
list<char> l(s, s + n);
for (auto ite = l.begin(); ite != l.end();)
{
bool flag = true;
auto ite2 = ite;
++ite2;
if (ite2 != l.end() && *ite2 == *ite)
{
auto ite3 = ite2;
++ite3;
if (ite3 != l.end() && *ite3 == *ite)
{
flag = false;
ans++;
if (ite == l.begin())
{
l.erase(ite, ++ite3);
ite = l.begin();
}
else
{
l.erase(ite--, ++ite3);
if (ite != l.begin()) --ite;
}
}
}
if (flag && ite != l.end())
++ite;
}
printf("%d", ans);
return 0;
}