Calculate pow(10, 9) C++

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C++14

for the following codeforces problem Problem - A - Codeforces[^]

My code produces a wrong output on

Test case (5) : 10 7
required a 10-digit-number divisible by 7 .

What I have tried:

int main(){
   
    int n, t;
    cin >> n >> t;
    
    if(n == 1 && t == 10)
        cout << "-1";
    if(t == 10)
        cout << 10 * pow(10,n-2);
    else
        cout << t * pow(10,n-1) << endl ;
    
    return 0;
}

The output from pow(7, 9) is (7e+009)
what does this symbols mean ?
Is this a drawback of pow(,) in C++ or it's me that misused it ?

N.B. I know another solution would be to print zeroes concatenated after the number or output 7777777777 . I want fixation to my solution and discover pow(,) more.