let inputCount = Int(readLine()!)!

let mod:Int64 = 1000000000 + 7
var ans:Int64 = 0
for _ in 0..<inputCount {
    let inpt = readLine()!.split(separator: " ").map({Int64($0)!})
    ans += ((inpt[0] / 2) % mod) * (inpt[1] % mod)
    ans = ans % mod
    if inpt[0] % 2 > 0 {
        ans += inpt[1]
    }
    ans = ans % mod
}

print(ans)