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fermatsInverse.cpp
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fermatsInverse.cpp
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#include <bits/stdc++.h>
using namespace std;
#define fast_cin() ios_base::sync_with_stdio(false)
#define pb push_back
#define ll long long
#define pii pair<int,int>
const int MAXN = 2e5+5;
// scanf("I64d %I64d", &l, &r);
#define TRACE
#ifdef TRACE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
const char* comma = strchr(names + 1, ',');cerr.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
}
#else
#define trace(...)
#endif
// applicable only when m is prime
int modInverse(int a, int m)
{
return modexpo(a, m-2, m);
}
int modexpo(int b, int e, int m)
{
int res = 1;
b = b%m;
while(e > 0)
{
if(e & 1)
res = (b*res)%m;
e = e/2;
res = (res*res)%m;
}
return res;
}
int main()
{
int a, m;
cin>>a>>m;
cout<<modInverse(a, m)<<'\n';
}