問題：A - 25個の文字列 #include <cstdio> #include <iostream> #include <string> using namespace std; int main(void) { string s; int n; cin >> s; scanf ("%d", &n); cout << s[(n - 1) / 5] << s[(n - 1) % 5] << "\n"; return 0; }</string></iostream></cstdio>