Stones

#include <bits/stdc++.h>

using namespace std;


int main() {
    //cin.sync_with_stdio(false);
    //stack<char> s;
    int last = getc(stdin);
    int num = 0;

    while (true) {
        int c = getc(stdin);
        if (c == EOF || c == '\n') {
            break;
        }

        if (c == last) {
            num++;
        } else {
            last = c;
        }
    }

    printf("%d\n", num);
    //cout << num << "\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