Forgotten measurements

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef uint64_t u64;

int main()
{
    string input;
    cin >> input;
    u64 out = 1;
    u64 i = 0;
    while (i < input.size())
    {
        if (input[i] == 'U' && input[i + 2] == 'D')
        {
            out++;
            input.erase(i, 4);
            i = i<2 ? 0 : i-2;
        }
        if (input[i] == 'D' && input[i + 2] == 'U')
        {
            out++;
            input.erase(i, 4);
            i = i<2 ? 0 : i-2;
        }
        if (input[i] == 'L' && input[i + 2] == 'R')
        {
            out++;
            input.erase(i, 4);
            i = i<2 ? 0 : i-2;
        }
        if (input[i] == 'R' && input[i + 2] == 'L')
        {
            out++;
            input.erase(i, 4);
            i = i<2 ? 0 : i-2;
        }
        i++;
    }
    cout << out;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: TIME LIMIT EXCEEDED

Test 9

Verdict: TIME LIMIT EXCEEDED

Test 10

Verdict: TIME LIMIT EXCEEDED

Test 11

Verdict: TIME LIMIT EXCEEDED