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#include <string>
#include <vector>

using namespace std;

int solution(vector<int> queue1, vector<int> queue2) {
    int answer = 0;
    long long sum1=0, sum2=0;
    for(int i=0;i<queue1.size();i++){
        sum1+=queue1[i];
    }
    for(int i=0;i<queue2.size();i++){
        sum2+=queue2[i];
    }
    if((sum1+sum2)%2==1)
        return -1;
    int size = queue1.size()+queue2.size();
    while(sum1!=sum2){
        if(answer>=size){
            answer = -1;
            break;
        }
        answer++;
        if(sum1>sum2){
            int temp = queue1[0];
            queue1.erase(queue1.begin());
            queue2.push_back(temp);
            sum1-=temp;
            sum2+=temp;
        }else{
            int temp = queue2[0];
            queue2.erase(queue2.begin());
            queue1.push_back(temp);
            sum2-=temp;
            sum1+=temp;
        }
    }
    return answer;
}