Language: C++

#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <algorithm>
#include <climits>
#include <cmath>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <vector>
using namespace std;

#define intmax INT_MAX
#define lmax LONG_MAX
#define uintmax UINT_MAX
#define ulmax ULONG_MAX
#define llmax LLONG_MAX
#define ll long long
#define rep(i, a, N) for ((i) = (a); (i) < (N); (i)++)
#define rrp(i, N, a) for ((i) = (N)-1; (i) >= (a); (i)--)
#define llfor ll i, j
#define sc(a) cin >> a
#define pr(a) cout << a << endl
#define pY puts("YES")
#define pN puts("NO")
#define py puts("Yes")
#define pn puts("No")
#define pnn printf("\n")
#define all(a) a.begin(), a.end()
#define push(a, b) (a).push_back(b)
#define llvec vector<vector<ll>>
#define charvec vector<vector<char>>
#define size(a, b) (a, vector<ll>(b))
#define llpvec vector<pair<ll, ll>>
double pi = acos(-1);
ll cei(ll x, ll y) {
    ll ans = x / y;
    if (x % y != 0) ans++;
    return ans;
}
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }
ll llpow(ll x, ll n) {
    ll i, ans = 1;
    rep(i, 0, n) ans *= x;
    return ans;
}
ll fact(ll x) {
    ll i, ans = 1;
    rep(i, 0, x) ans *= (x - i);
    return ans;
}
ll ncr(ll n, ll r) { return fact(n) / fact(r) / fact(n - r); }
ll npr(ll n, ll r) { return fact(n) / fact(n - r); }
bool prime(ll a) {
    if (a <= 1) return false;
    ll i;
    for (i = 2; i * i <= a; i++) {
        if (a % i == 0) return false;
    }
    return true;
}
ll fib(ll x) {
    ll i, fibo[x + 10];
    fibo[0] = 1;
    fibo[1] = 1;
    fibo[2] = 1;
    rep(i, 3, x + 1) fibo[i] = fibo[i - 1] + fibo[i - 2];
    return fibo[x];
}
ll dig(ll n) {
    ll d = 0, i = 0;
    while (n / 10 > 0) {
        i++;
        d++;
    }
    return d;
}
llfor;
ll ans = 0;
int main() {
    ll h, w;
    cin >> h >> w;
    char t[10], s[10] = "snuke";
    rep(i, 0, h) {
        rep(j, 0, w) {
            sc(t);
            if (!strcmp(s, t)) {
                char c = 'A' + j;
                cout << c << i + 1 << endl;
                return 0;
            }
        }
    }

    return 0;
}

Example test case(s):
input: 15 10
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snuke snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake
snake snake snake snake snake snake snake snake snake snake

output: H6