function processData(input) {
    let s1 = [], s2 = []
    let inputs = input.split('\n')
    for (let i = 1; i < inputs.length; i++) {
        let arr = inputs[i].split(' ')
        switch (arr[0]) {
            case '1': {
                s1.push(arr[1])
                break
            }
            case '2': {
                while (s1.length > 0) s2.push(s1.pop())
                s2.pop()
                while (s2.length > 0) s1.push(s2.pop())
                break
            }
            case '3': {
                console.log(s1[0])
                break
            }
        }
    }
}