MOD = 10**9 + 7  # 定义模数10^9+7

def mod_exp(base, exponent, mod):
    result = 1
    base %= mod
    while exponent > 0:
        if exponent % 2 == 1:
            result = (result * base) % mod
        base = (base * base) % mod
        exponent //= 2
    return result

def main():
    s = input().strip()
    k = int(input().strip())

    n = len(s)
    u = sum(1 for c in s if 'A' <= c <= 'Z')

    if k == 0:
        print(n % MOD)
        return

    # 正确调用：使用变量 k 作为指数
    two_k = mod_exp(2, k, MOD)

    ans = (n + u * ((two_k - 1) % MOD)) % MOD
    print(ans)

if __name__ == "__main__":
    main()

import java.util.Scanner;

public class Main {
    // 定义模数10^9+7
    static final long MOD = 1000000007;


    public static long modExp(long base, long exponent, long mod) {
        long result = 1;
        base %= mod;
        while (exponent > 0) {
            // 如果当前指数为奇数，更新结果
            if ((exponent & 1) == 1) {
                result = (result * base) % mod;
            }
            base = (base * base) % mod;  // 底数自乘
            exponent >>= 1;              // 指数右移1位
        }
        return result;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        // 读入初始字符串s和操作次数k
        String s = sc.next();
        long k = sc.nextLong();

        int n = s.length();  // 初始字符串长度n
        int u = 0;           // 初始活跃字符（大写字母）个数u
        // 遍历字符串统计活跃字符
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c >= 'A' && c <= 'Z') {
                u++;
            }
        }

        // 当操作次数为0时，直接输出初始字符串长度
        if (k == 0) {
            System.out.println(n % MOD);
            return;
        }

        // 计算2^k mod MOD
        long twoK = modExp(2, k, MOD);

        // 根据公式L_k = n + u(2^k - 1)得到最终字符串的长度
        long ans = (n + u * ((twoK - 1 + MOD) % MOD)) % MOD;
        System.out.println(ans);
    }
}