int truckTour(vector<vector<int>> petrolpumps) {
int balance,deficit,start=1;

for(int i =0;i<petrolpumps.size();i++){
    balance += petrolpumps[i][0] - petrolpumps[i][1];

    if(balance < 0){
        deficit += balance;
        start = i+1;
        balance = 0;
    }
}
if(balance + deficit >= 0){
    return start;
}
return -1;
}