Stones

#include <bits/stdc++.h>
using namespace std;

int main() {
	string s;
	cin>>s;
	int cnt=0;
	char mem=s[0];
	for (unsigned int i=1;i<s.size();i++) {
		if (s[i]==mem) cnt++;
		mem=s[i];
	}
	cout<<cnt<<"\n";

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED