function processData(input) {
    //Enter your code here
    let numberOfOpps = parseInt(input[0]);
    let inputs = input.split("\n").slice(1); 
    let stack = []; 
    let currentString = ""; 
    for(let i = 0; i < numberOfOpps; i++){ 
         let opperation = inputs[i].split(" "); 
         let code = parseInt(opperation[0]); 
         let string = opperation[1];
         if(code == 1){ 
            stack.push(currentString); 
            currentString = currentString.concat(string); 
            // console.log("CURRENT STRING", currentString); 
         }else if (code == 2){ 
            stack.push(currentString); 
            let index = (currentString.length - parseInt(string) -1);
            if(index <= 0){ 
                currentString = ""; 
            }else{
                currentString = currentString.slice(0, index);
            }
            // console.log("CURRENT STRING", currentString);
         }else if (code == 3){ 
            let index = (parseInt(string) - 1);
             console.log(currentString[index]);
         }else if(code == 4){ 
            currentString = stack.pop(); 
            // console.log("CURRENT STRING", currentString);
         }
    }
}