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| template<typename T, int M>
struct matrix_t {
using row = vector<T>;
using mat = vector<row>;
using ll = long long;
static void mul(const mat& a, const mat& b, mat& c) {
auto m = a.size(), p = a[0].size(), n = b[0].size();
for (int i = 0; i < m; ++i) {
for (int k = 0; k < p; ++k) {
for (int j = 0; j < n; ++j) {
c[i][j] = (c[i][j] + (ll)a[i][k] * b[k][j]) % M;
}
}
}
}
static mat mul(const mat& a, const mat& b) {
auto m = a.size(), n = b[0].size();
mat c = vector<row>(m, row(n, 0));
mul(a, b, c);
return c;
}
static mat qpow(mat a, ll k) {
auto n = a.size();
mat ans = vector<row>(n, row(n, 0));
for (int i = 0; i < n; ++i) {
ans[i][i] = 1;
}
while (k) {
if (k & 1) {
ans = mul(a, ans);
}
k >>= 1;
a = mul(a, a);
}
return ans;
}
};
const int M = 1e9 + 7;
using matrix = matrix_t<int, M>;
class Solution {
public:
int fib(int n) {
vector<vector<int>> mat = {{0, 1}, {1, 1}};
vector<vector<int>> vec = {{0, 1}};
mat = matrix::qpow(mat, n);
return matrix::mul(vec, mat)[0][0];
}
};
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