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1 #include <iostream> 2 #include <string.h> 3 #include <cstdio> 4 #include <queue> 5 #include <map> 6 #include <vector> 7 #include <string> 8 #include <cstring> 9 #include <algorithm> 10 #include <math.h> 11 12 #define SIGMA_SIZE 26 13 #pragma warning ( disable : 4996 ) 14 15 using namespace std; 16 typedef long long LL; 17 18 inline LL LMax(LL a,LL b) { return a>b?a:b; } 19 inline LL LMin(LL a,LL b) { return a>b?b:a; } 20 inline int Max(int a,int b) { return a>b?a:b; } 21 inline int Min(int a,int b) { return a>b?b:a; } 22 inline int gcd( int a, int b ) { return b==0?a:gcd(b,a%b); } 23 inline int lcm( int a, int b ) { return a/gcd(a,b)*b; } //a*b = gcd*lcm 24 const LL INF = 0x3f3f3f3f3f3f3f3f; 25 const LL mod = 1000000007; 26 const int inf = 0x3f3f3f3f; 27 const int maxk = 1e5+5; 28 const int maxn = 1e5+5; 29 30 int K; 31 char str[maxn]; 32 33 //计算a的b次方取模 34 LL getm( LL a, LL b, LL m ) 35 { 36 LL ans = 1, base = a; 37 while( b ) 38 { 39 if ( b & 1 ) 40 ans = (ans * base) % m; 41 base = ( base * base ) % m; 42 b >>= 1; 43 } 44 return ans; 45 } 46 47 // 求a关于p的逆元 48 LL getn( LL a, LL p ) 49 { return getm( a, p-2, p ); } 50 51 int main() 52 { 53 cin >> K; 54 scanf( "%s", str ); 55 56 LL ans = 0; 57 int len = strlen(str); 58 59 LL inv, a1 = 0; 60 LL p = 1, tmp = getm( 2, len, mod ); 61 LL sum = 0; 62 63 64 65 p = getm( tmp, K, mod ); 66 inv = getn( tmp-1, mod ); 67 sum = ( ((p-1)%mod) * (inv%mod) ) %mod; 68 69 for (int i = len - 1; i >= 0; i--) 70 { 71 if (str[i] == '0' || str[i] == '5') 72 { 73 a1 = getm( 2, i, mod ); 74 ans += (a1*sum)%mod; 75 ans %= mod; 76 } 77 } 78 79 printf( "%lld ", ans ); 80 81 return 0; 82 }