// Template for Palindrome
#include<cstdio>
 
// We don't know in advance how many characters will be in the input
//
// That's why we make the array big enough to contain the
// largest possible input. Actually, we need to make it one bigger
// than the largest possible input. I won't explain here, but you
// can take a look at https://www.learncpp.com/cpp-tutorial/c-style-strings/
// if you're curious.
char line[100001];
int N;
int main() {
    // Read the input.
    // Notice that unlike with reading integers, we don't have an
    // ampersand (&) before "line".
    //
    // Notice that although N and the string are on different lines,
    // we still only separate them by a space in the format string ("%d %s").
    // This is because a space in the format string actually means "any number
    // of whitespace characters" (which includes spaces, tabs and newlines).
    scanf("%d %s", &N, line);
    
    for(int i = 0; i < N; i++) {
        // TODO: Replace this with a proper solution
        line[i] = '?';
    }
 
    printf("%s\n", line);
}