Triangle ABC is isosceles if and only if one of \(a=b\), \(b=c\), or \(c=a\) holds.
This can be checked using an if statement.

Sample code in C++:

#include <bits/stdc++.h>

using namespace std;

int main(void){
	int a,b,c;
	cin>>a>>b>>c;
	if((a==b)|(b==c)|(c==a))cout<<"Yes"<<endl;
	else cout<<"No"<<endl;
	return 0;
}

Sample code in Python:

a,b,c=map(int, input().split())

if a==b or b==c or c==a:
    print("Yes")
else:
    print("No")