Bit string

input/code.cpp: In function 'int main()':
input/code.cpp:12:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (ctr1=0;ctr1<sis.length();ctr1++){
                 ~~~~^~~~~~~~~~~~~
input/code.cpp:15:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (ctr2=ctr1;ctr2<sis.length();ctr2++){
                        ~~~~^~~~~~~~~~~~~

#include <iostream>

int main(){
    std::string sis;
    std::cin >> sis;
    int ctr1=0;
    int ctr2=1;
    /*if ((sis[0] == '0' && sis[1] == '0') || (sis[0] == '1' && sis[1] == '1')){
        paaris = true;
    }*/
    int sum =0;
    for (ctr1=0;ctr1<sis.length();ctr1++){
        bool paaris = true;
        if (sis[ctr1] == '1')paaris = !paaris;
        for (ctr2=ctr1;ctr2<sis.length();ctr2++){
            if (sis[ctr2] == '1' && ctr1 != ctr2)paaris = !paaris;
            if (paaris) sum++;
        }
    }
    std::cout << sum <<'\n';
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 1

Verdict: ACCEPTED

Test 7

Group: 1

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 16

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 17

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 18

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 19

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 20

Group: 3

Verdict: ACCEPTED

Test 21

Group: 3

Verdict: ACCEPTED