1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <numeric>

using namespace std;
using ull = unsigned long long;


#ifdef GGDEBUG
#define dbg printf
#else 
#define dbg //dbg
#endif


int p = 1000000000 + 7;

// logarithmic power
ull power_of_two(int pwr) {
    if (pwr == 0) return 1;
    if (pwr % 2 == 0) {
        ull tmp = power_of_two(pwr / 2);
        tmp *= tmp;
        tmp %= p;
        return tmp;
    }

    ull tmp = 2 * power_of_two(pwr - 1);
    tmp %= p;
    return tmp;
}


int main() {
    int n;
    scanf("%d", &n);

    vector<int> in;
    ull sum_of_all = 0;
    
    for (int i = 0; i < n; i++) {
        int x;
        scanf("%d", &x);
        in.push_back(x);

        sum_of_all += x;
    }

    if (sum_of_all < p) {
        // find number of separate groups
        ull sum = 0;
        int groups = 0;

        for (int i = 0; i < n; i++) {
            dbg("%d ", in[i]);
        }
        dbg("\n");


        for (int i = 0; i < n; i++) {
            sum += in[i];
            if (sum % 2 == 0) {
                groups++;
                sum = 0;
            }
        }
        if (sum != 0) {
            printf("0\n");
            return 0;
        }

        dbg("groups: %d\n", groups);
        cout << power_of_two(groups-1) << endl;

        return 0;
    } else {
        vector<int> poss;
        poss.resize(n+1, 0);
        poss[n] = 1;

        for (int i = n-1; i >= 0; i--) {
            // dbg("%d ", in[i]);

            ull sum = 0;
            for (int j = i; j < n; j++) {
                sum += in[j];
                sum %= p;
                if ((sum % p) % 2 == 0) {
                    poss[i] += poss[j+1];
                    poss[i] %= p;
                }
            }
        }

        for (int i = 0; i < n; i++) {
            dbg("%d ", poss[i]);
        }
        dbg("\n");

        cout << poss[0] << endl;
    }

    return 0;
}