function processData(input) {
    let queries = input.split('\n');
    let q = parseInt(queries[0]);  
    let stack1 = [];
    let stack2 = [];
    for (let i = 1; i <= q; i++) {
        let query = queries[i].split('  ');
        let type = parseInt(query[0]);
        if (type === 1) {
             
            let x = parseInt(query[1]);
            stack1.push(x);
        } else if (type === 2) {
            if (stack2.length === 0) {
                while (stack1.length > 0) {
                    stack2.push(stack1.pop());
                }
            }
            stack2.pop();
        } else if (type === 3) {
            if (stack2.length === 0) {
                while (stack1.length > 0) {
                    stack2.push(stack1.pop());
                }
            }
            console.log(stack2[stack2.length - 1]);  
        }
    }
}