import std;

void main() {
    int L;
    readf("%d\n", L);

    auto P = new ulong[](L), e = new ulong[](L);
    foreach (i; 0 .. L) readf("%d %d\n", P[i], e[i]);

    enum ulong M = 10 ^^ 9 + 7;

    ulong res = 1;
    foreach (i; 0 .. L) {
        ulong v = powmod(P[i]-1, M-2, M);
        ulong s = v * v % M;

        ulong num = powmod(P[i], e[i]+2, M);
        res = (res * ((s * (num + M - P[i]) % M) + M - v * (e[i] + 1) % M)) % M;
    }

    res.writeln;
}