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
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
#include <algorithm>
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <vector>

int c;

#define SKIP_WHITESPACE \
{   \
    while (1) { \
        c = fgetc(stdin);   \
        if (c != ' ' && c != '\n' && c != '\r') \
            break;  \
    }   \
}   \

#define READ_INT    \
({   \
    SKIP_WHITESPACE \
    int ret = c - '0';  \
    while (1) { \
        c = fgetc(stdin);   \
        if (c < '0' || c > '9') \
            break;  \
        ret = ret * 10 + c - '0';   \
    }   \
    ret; \
})   \

#define MOD 1000000007ULL

struct bulb {
    int init;
    int witches;
    int kol;
};

struct witch {
    int par;
    int next;
};

uint64_t powers[20];

uint64_t power(int pn) {
    int pi = 0;
    uint64_t pret = 1ULL;
    while (pn > 0) {
        if (pn & 1) {
            pret = (pret * powers[pi]) % MOD;
        }
        pi++;
        pn = pn >> 1;
    }
    return pret;
}

uint64_t inv(uint64_t inva) {
  return inva <= 1 ? inva : MOD - (uint64_t)(MOD / inva) * inv(MOD % inva) % MOD;
}

uint64_t newton(int nn, int nk) {
    if (nk > (nn - nk))
        nk = nn - nk;

    if (nk == 0)
        return 1ULL;
    if (nk == 1)
        return uint64_t(nn);

    uint64_t top = nn;
    uint64_t bottom = nk;
    while ( nk > 1 ) {
        nk--;
        top = (top * (nn - nk)) % MOD;
        bottom = (bottom * nk) % MOD;
    }
    return (top * inv(bottom)) % MOD;
}

int main(int argc, char* argv[]) {
    std::ios_base::sync_with_stdio (false);
    int i, t, a, b, w, n, m;

    powers[0] = 2ULL;
    for (i = 1; i < 20; ++i) {
        powers[i] = (powers[i - 1] * powers[i - 1]) % MOD;
    }

    n = READ_INT;
    m = READ_INT;

    std::vector<bulb> bulbs(n);
    std::vector<witch> witches(m * 2);
    int wi = 0;
    std::vector<int> stack(n);
    int si = 0;

    for (i = 0; i < n; ++i) {
        t = READ_INT;
        bulbs[i] = {t, -1, -1};
    }

    for (i = 0; i < m; ++i) {
        a = READ_INT - 1;
        b = READ_INT - 1;

        witches[wi] = {b, bulbs[a].witches};
        bulbs[a].witches = wi;
        wi++;

        witches[wi] = {a, bulbs[b].witches};
        bulbs[b].witches = wi;
        wi++;
    }

    // for (i = 0; i < n; ++i) {
    //     std::cout << "bulb: " << i << "; init=" << bulbs[i].init << "; switches={";
    //     w = bulbs[i].witches;
    //     while (w != -1) {
    //         std::cout << witches[w].par << ", ";
    //         w = witches[w].next;
    //     }
    //     std::cout << "}\n";
    // }

    int kol, z[2], s[2], idx, par, oddcycle;
    uint64_t ret = 1ULL, klik;

    for (i = 0; i < n; ++i) {
        if (bulbs[i].kol != -1) continue;

        bulbs[i].kol = 0;
        z[0] = 1;
        z[1] = 0;
        s[0] = bulbs[i].init;
        s[1] = 0;
        oddcycle = 0;

        stack[0] = i;
        si = 1;

        while (si > 0) {
            idx = stack[--si];
            w = bulbs[idx].witches;
            kol = bulbs[idx].kol ^ 1;
            while (w != -1) {
                par = witches[w].par;
                if (bulbs[par].kol == -1) {
                    bulbs[par].kol = kol;
                    z[kol]++;
                    s[kol] += bulbs[par].init;
                    stack[si++] = par;
                } else if (bulbs[par].kol == bulbs[idx].kol) {
                    oddcycle = 1;
                }
                w = witches[w].next;
            }
        }
        if (oddcycle) {
            klik = power(z[0] + z[1] - 1);
        } else {
            klik = newton(z[0] + z[1], z[0] - s[0] + s[1]);
        }
        ret = (ret * klik) % MOD;
//        std::cout << "oc=" << oddcycle << "; z=" << z[0] << "; c=" << z[1] << "; s=" << s[0] << "; p=" << s[1] << "; klik=" << klik << "\n";
    }
    std::cout << ret;
    std::cout << "\n";

    return EXIT_SUCCESS;
}