C++ solution using the set theory concepts
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity: O(NlogN)\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity: O(1)\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\ntypedef long long int ll;\nconst int mod=1e9+7;\n\nclass Solution {\npublic:\n\n    ll fastPower(ll a,ll b){\n        ll ans=1;\n        while(b){\n           if (b&1) ans=(ans*a)%mod;\n            a=(a*a)%mod;\n            b/=2;\n        }\n        return ans;\n    }\n\n    int stringCount(int n) {\n        ll total=fastPower(26,n);\n        ll a=(fastPower(25,n-1)*(n+75))%mod;\n        ll b=(fastPower(24,n-1)*(2*n+72))%mod;\n        ll c=(fastPower(23,n-1)*(n+23))%mod;\n\n        ll d=(a-b+c+mod)%mod;\n\n        ll ans=(total-d+mod)%mod;\n\n        return ans;\n        \n    }\n};\n```
['C++']