ccf csp 201803-1 跳一跳

#include<iostream>
using namespace std;

int main(){
    int state, prev = 1, tot = 0;
    while(true){
        cin >> state;
        if(state == 0){
            break;
        }else if(state == 1){
            tot += 1;
            prev = 1;
        }else{
            if(prev == 1){
                tot += 2;
                prev = 2;
            }else{
                tot += prev + 2;
                prev += 2;
            }
        }
    }
    cout << tot << endl;

    return 0;
}