#include <bits/stdc++.h>
#include <iostream>
using namespace std;


class ModInt
{
public:
    static int _BM;
    long long int m_value;
    ModInt()
    {
        m_value = 0;
    }

    ModInt(int v)
    {
        m_value = (long long int) v;
    }

    ModInt(const ModInt &t)
    {
        m_value = t.getint();
    }

    int operator + (const ModInt &t) 
    {
		return ModInt::modadd(getint(), t.getint());
	}    

    int operator + (int t) 
    {
		return ModInt::modadd(getint(), t);
	}      

    int operator -  (const ModInt &t) 
    {
		return ModInt::modminus(getint(), t.getint());
	}    
    int operator - (int t) 
    {
		return ModInt::modminus(getint(), t);
	}  

    int operator * (const ModInt &t) 
    {
		return ModInt::modmul(getint(), t.getint());
	}  
    int operator * (int t) 
    {
		return ModInt::modmul(getint(), t);
	} 

    ModInt& operator += ( const ModInt &t )
    {
        (*this) += t.getint();
        return (*this);
    }


    ModInt& operator *= ( const ModInt &t )
    {
        (*this) *= t.getint();
        return (*this);
    }

    ModInt& operator -= ( const ModInt &t )
    {
        (*this) -= t.getint();
        return (*this);
    }

    ModInt& operator += ( int v )
    {
        m_value += v;
        if(m_value >= _BM) m_value -= _BM;
        return *this;
    }

    ModInt& operator -= ( int v )
    {
        m_value -= v;
        if( m_value < 0 ) m_value += _BM;
        return *this;
    }

    ModInt& operator *= ( int v )
    {
        m_value *= v;
        m_value %= _BM;
        return *this;
    }

    static int modadd( int a, int b )
    {
        ModInt t(a);
        t += b;
        return t.getint();
    }

    static int modminus( int a, int b )
    {
        ModInt t(a);
        t -= b;
        return t.getint();
    }    

    static int modmul( int a, int b )
    {
        ModInt t(a);
        t *= b;
        return t.getint();
    }

    // a^b;
    static int modpow(int a, int b)
    {
        ModInt ans(1);
        int heap[32];
        heap[0] = a;
        for( int bit = 0; b >= (1 << bit); bit++ )
        {
            if( bit > 0 ) heap[bit] = modmul( heap[bit - 1], heap[bit - 1] );
            if( b & (1 << bit) )
            {
                ans *= heap[bit];
            }
        }
        return ans.getint();
    }

    static int reciprocal(int a)
    {
        return modpow(a, _BM - 2);
    }

    static int combination(int n, int r)
    {
        int *fac = (int *)malloc(sizeof(int) * (n + 1));
        int *facinv = (int *)malloc(sizeof(int) * (n + 1));
        fac[0] = 1;
        for( int k = 1; k <= n; k++) fac[k] = modmul(k, fac[k - 1]);
        facinv[n] = reciprocal( fac[n] );
        for( int k = n ; k > 0; k--) facinv[k - 1] = modmul(k, facinv[k]);

        ModInt ans(fac[n]);
        ans *= facinv[r];
        ans *= facinv[n - r];

        free(fac);
        free(facinv);
        return ans.getint();
    }

    int getint() const
    {
        return (int) m_value;
    }


private:
    void _mod()
    {
        m_value %= _BM;
    }
};

int ModInt::_BM = 1000000007;

class ModFactorial
{
public:
    int m_max;
    int *m_factorial;
    int *m_factorialinv;

    ModFactorial(int max)
    {
        m_max = max;
        m_factorial = (int*) malloc(sizeof(int) * m_max );
        m_factorialinv = (int*) malloc(sizeof(int) * m_max );
 
        m_factorial[0] = 1;
        for( int k = 1; k < m_max; k++) m_factorial[k] = ModInt::modmul(k, m_factorial[k - 1]);
        m_factorialinv[m_max - 1] = ModInt::reciprocal( m_factorial[m_max - 1] );
        for( int k = m_max - 1 ; k > 0; k--) m_factorialinv[k - 1] = ModInt::modmul(k, m_factorialinv[k]);
    }

    ~ModFactorial()
    {
        free(m_factorial);
        free(m_factorialinv);
    }

    int getFactorial(int n)
    {
        return m_factorial[n];
    }

    int getCombination(int n, int r)
    {
        ModInt ans(m_factorial[n]);
        ans *= m_factorialinv[r];
        ans *= m_factorialinv[n - r];
        return ans.getint();
    }
};


int main()
{
    int k;
    string s;
    cin >> k;
    getline(cin, s);
    getline(cin, s);
    int n = 0;
    for(int i = 0; i < s.length(); i++ )
    {
        if( s[i] >= 'a' && s[i] <= 'z' ) n++;
    }

    int t = n + k;

    ModFactorial f(t + 1);

    ModInt ans = ModInt::modpow(26, t);
    for( int i = 0; i < n; i++ )
    {
        ModInt tmp = f.getCombination(t, i);
        tmp *= ModInt::modpow(25, t - i);
        ans -= tmp;
    }

    cout << ans.getint();
    
    return 0;    
}

Measured memory_bytes: 19976